Best Place to Buy Boat Parts Online: Marine Parts Price Guide (2026)

I've been wrenching on outboards for over a decade — a Mercury 150 FourStroke on a bass boat and a pair of Yamaha F115s on a center console. Marine dealer markup is legitimately brutal. A water pump impeller kit that costs $18 at iBoats is $45 at the marina. A fuel pump that's $120 online hits $210 at the counter. Here's every major online source ranked honestly, with real prices on the parts you actually need.

Why Marine Parts Are So Expensive at Dealerships

Marine engine parts are expensive for structural reasons that won't change soon. The market is small — there are roughly 11 million registered motorized boats in the US compared to 280 million registered vehicles. That low volume means dealers stock less, turn inventory slower, and carry higher per-unit overhead. When a part sits on a shelf for six months, someone pays for that capital — and it's you, at the counter.

The other driver is OEM lock-in. Mercury Marine's SmartCraft system and Yamaha's Command Module Display (CMD) electronics require proprietary tools and software to calibrate. Dealers who own that software have a captive audience for diagnostics, and parts pricing reflects that. For non-electronic mechanical components — impellers, fuel pumps, zincs, filters — there's a robust aftermarket and the savings online are substantial. For ECU-dependent components, a dealer relationship matters.

The Main Online Retailers — Ranked and Honest

iBoats — Best All-Around for Outboard Parts

iBoats is the best starting point for outboard motor parts. Their catalog integrates OEM cross-reference so you can enter a Mercury or Yamaha part number and see both OEM and aftermarket equivalents side by side. They carry a strong selection of Quicksilver (Mercury's own aftermarket brand) and Sierra Marine aftermarket parts — both legitimate manufacturers used widely in the industry.

iBoats is strong on engine internals: impeller kits, water pump housings, fuel pumps, thermostats, and lower unit gear oil. Their YMM (year/make/model/horsepower) search filters results to confirmed-fit parts, which matters on outboards where a 1-year difference in the model can mean a different part number.

West Marine — Good for Electrical and Rigging, Expensive on Engine Parts

West Marine is the Home Depot of boating — 240+ retail locations, solid online store, recognizable brand. Where they shine: electrical (marine-grade wire, connectors, circuit breakers, battery switches), safety gear (PFDs, flares, EPIRBs), rigging hardware, and dock accessories. Their sourcing on those categories is well-curated and the quality is reliable.

Engine parts, however, are not West Marine's strength. Pricing on impeller kits, fuel filters, and zincs runs 20–35% higher than iBoats or Amazon for the same part. Use West Marine when you need something today (local store pickup) or for non-engine marine equipment. Check prices before defaulting to them for engine consumables.

Defender Industries — Best for Cruising and Sailboat Equipment

Defender is the specialist for cruising sailors and liveaboards. Their catalog runs deep on electrical systems, DC power management, navigation electronics, watermakers, and rigging. They carry Blue Sea Systems, Victron Energy, Garmin, Furuno, and a wide range of cruising-specific hardware that West Marine doesn't stock.

For powerboat outboard parts, Defender is not the first call — their engine parts catalog is thinner. For anything electrical on a sailboat or cruising powerboat, Defender often has parts West Marine won't stock and at better prices.

Overton's — Best for Accessories, Covers, and Upholstery

Overton's is the go-to for recreational boat accessories: custom boat covers, bimini tops, upholstery foam and fabric, ski ropes, tube towables, boarding ladders, fenders, and dock lines. Their pricing on covers and accessories is consistently competitive. They're not an engine parts source — don't look for impellers here. But if you need a new pontoon cover or replacement seat foam, Overton's is the right call.

Go2Marine — Best for Commercial and Workboat Parts

Go2Marine serves commercial fishing vessels, workboats, and charter operations — their catalog skews toward heavy-duty components. Strong on commercial-grade electrical, navigation lights that meet USCG commercial specifications, winches, and commercial anchor hardware. If you run a serious working vessel, Go2Marine stocks what West Marine doesn't. For recreational outboard owners, it's less relevant — but if you're running twin 250s on a charter boat, it's worth bookmarking.

Amazon — Right for Consumables, Risky on OEM-Specific Parts

Amazon works well for a specific slice of marine parts: impeller kits from known brands (CEF, Sierra), zinc anode sets, oil filters, spark plugs, and props from established manufacturers (Solas, Michigan Wheel). These are items where fitment is simple, quality is verifiable by brand name, and Amazon's price and Prime shipping make sense.

Where Amazon gets dangerous: OEM-specific electronic components, Mercury SmartCraft sensors, Yamaha control modules, and anything where a fitment error means installation damage. Amazon's marine catalog has significant fitment data problems — third-party sellers copy application listings without verifying fit. On a $12 zinc, that's a minor inconvenience. On a fuel management module, it's a real risk.

The same online vs. local tradeoff analysis from our RockAuto vs. AutoZone breakdown applies directly here — the discipline of verifying fitment before ordering saves money and headaches across any vehicle category.

Rocky Mountain ATV/MC — Hidden Gem for PWC Parts

Rocky Mountain ATV/MC built their reputation in powersports, but their marine section covers Sea-Doo, WaveRunner (Yamaha), and Kawasaki Jet Ski parts at pricing that undercuts most specialty marine retailers. If you run a PWC, Rocky Mountain is the most underrated source most riders haven't found yet.

Head-to-Head: 5 Parts, Real 2026 Prices

These are realistic price ranges based on 2025–2026 market pricing. Your specific application may vary — always verify fitment before ordering.

Mercury 4-Stroke Fuel Pump (8M0047304)

This is one of the most commonly replaced Mercury FourStroke parts. At a Mercury dealer you're looking at $195–$225 for OEM. iBoats carries the Sierra equivalent (Sierra 18-7350) at $105–$130 — the same spec, different label, made to OEM tolerances. Amazon carries it too at comparable pricing. West Marine will have it but at a premium. Skip the dealer on this one unless it's a warranty situation.

Yamaha F115 Impeller Kit

Impellers are the most commonly neglected maintenance item on 4-stroke outboards — every 200 hours or 3 years, whichever comes first. Yamaha dealer price for the OEM kit: $55–$75. The Sierra equivalent or a CEF kit from iBoats runs $22–$32. Amazon has similar pricing from known brands. This is the classic "buy aftermarket from a real brand" scenario — Sierra and CEF impellers are the correct choice. See the OEM vs. aftermarket section below.

Zinc Anode Set (Cavitation Plate)

Zincs are pure commodity — the spec is the alloy, and verified marine-grade zinc from any established supplier works the same. Amazon wins on zinc pricing consistently, often $9–$15 for a full set vs. $28–$40 at the marina. Buy a year's supply at once and don't overthink it.

Sierra Marine Oil Filter (Quicksilver 35-877761Q01 Equivalent)

The Quicksilver 35-877761Q01 is the standard oil filter for Mercury 4-stroke outboards. Mercury dealer price: $18–$25 each. The Sierra 18-7896 is a direct OEM-equivalent at $8–$12 from iBoats or Amazon. Buy a six-pack. This is exactly the part category where you stop paying dealer prices with zero quality tradeoff.

Stainless Prop (3-Blade, 10.5" Pitch, 40–60hp)

Props are where Amazon pulls ahead on price — Solas and Michigan Wheel props on Amazon run $110–$160 vs. $220–$290 at a dealer for OEM aluminum/stainless comparable. The caveat: prop pitch and hub configuration matter for your specific motor. Use the prop manufacturer's fitment tool, verify the hub kit compatibility, and don't just order by pitch alone. Solas props on Amazon are legitimate — Solas is a major OEM prop supplier, not a knockoff brand.

OEM vs. Aftermarket: What's Actually Safe

Aftermarket Brands Worth Trusting

• Sierra Marine — The gold standard for Mercury and Yamaha aftermarket. Sierra makes OEM-quality impeller kits, fuel pumps, filters, and thermostats. If iBoats or Amazon lists it as Sierra, it's the right choice.
• CEF (formerly Mallory) — Strong on impeller kits and water pump components. Long-established marine aftermarket brand. CEF impellers are used by professional marine mechanics as a matter of routine.
• Mallory Marine — Same lineage as CEF, strong on ignition components: distributor caps, rotors, spark plug wires for older carbureted outboards.
• Solas — The correct choice for aftermarket props. Solas manufactures propellers for OEMs — they're not a knockoff brand.
• Quicksilver — Mercury's own aftermarket brand (not the OEM service parts). Available through iBoats and some Amazon sellers at prices below Mercury dealer.

What to Avoid

Any impeller kit, fuel pump, or water pump housing from an unnamed Chinese manufacturer with no brand clearly stated. These circulate on Amazon and eBay under titles like "Compatible with Mercury 150 Impeller Kit" with no brand name in the listing. The materials spec on impeller rubber is specific — it has to flex at the right temperature range and resist deterioration from ethanol-blended fuel. Unknown rubber compounds fail, often catastrophically. If you can't identify the manufacturer, don't buy it for any water-contact engine component.

PWC Parts: Sea-Doo and WaveRunner

Personal watercraft parts are their own market. Sea-Doo (BRP) and WaveRunner (Yamaha) parts pricing at dealers is punishing — $80 for an oil filter, $120 for an impeller that's $35 online. Here's where to buy:

• Rocky Mountain ATV/MC — Best pricing on PWC maintenance parts. Their Sea-Doo and WaveRunner coverage is deep: impellers, wear rings, spark plugs, oil filters, oil, and pump shaft seals. This is the go-to source most PWC owners haven't found yet.
• iBoats — Good OEM cross-reference for PWC parts, especially on older Sea-Doo models where getting the right part number matters.
• Amazon — Solid on consumables: spark plugs, oil, oil filters, zinc anodes. Stick to brand-name sellers (Sierra, NGK, OEM-grade suppliers). The same fitment caution applies — verify part numbers before buying anything engine-internal on Amazon for PWC.

For Sea-Doo 4-TEC (GTI, GTX, RXP, RXT) and Yamaha FX/VX series WaveRunners, impeller replacement is a common DIY job — Rocky Mountain prices these at 40–50% below BRP and Yamaha dealer pricing. If you haven't checked Rocky Mountain yet, start there before your next PWC service.

The Expert Tier: OEM Diagnostics for Mercury and Yamaha

If you run a Mercury or Yamaha outboard and wrench on it yourself, the single most useful thing you can add is access to OEM diagnostic software. Mercury's Mercury Connect and Yamaha's diagnostic software give you fault code definitions, wiring diagrams, and fuel trim data that generic NMEA tools won't surface.

The PartsPulse Expert tier includes access to Mercury Connect and Yamaha diagnostic portals — the same OEM tools the dealer uses to pull and clear codes, read sensor data, and verify trim/tilt calibration. If you're spending real money diagnosing a rough-running FourStroke or an erratic trim system, having the right tool changes everything.

See the Expert tier at the pricing page →

Where to Buy — The Short Answer

• OEM engine parts, cross-reference, Quicksilver/Sierra selection → iBoats
• Electrical, safety gear, rigging → West Marine
• Sailboat/cruising electrical and systems → Defender Industries
• Boat covers, accessories, upholstery → Overton's
• Commercial/workboat components → Go2Marine
• Zincs, filters, props, consumables → Amazon (verified brands only)
• Sea-Doo and WaveRunner parts → Rocky Mountain ATV/MC
• Impellers, fuel pumps, water pump kits → Sierra/CEF brands from iBoats or Amazon — never unknown no-name

The marine parts market rewards the buyer who checks prices before clicking. Dealer markup is real, the savings are meaningful, and the aftermarket brands (Sierra, CEF, Solas, Quicksilver) are good enough that you're not trading quality for price.