Cost + timeline for an auto-parts Magento build — realistic numbers?

Realistic ranges for an auto-parts retailer at $3M–$15M GMV:

• Magento + Hyvä rebuild: $35k–$120k. Auto-parts-specific scope adds: YMM data integration ($6k–$12k), VIN decode endpoint ($2k–$4k), OEM cross-reference setup ($4k–$8k), LTL freight integration via FreightCenter / ShipperHQ ($5k–$10k), hazmat workflow ($3k–$6k), CARB / DOT compliance attributes + checkout blocks ($3k–$5k), fleet B2B layer ($10k–$30k depending on complexity), warranty + recall workflow ($4k–$10k), marketplace integration if needed (eBay Motors, Amazon Garage: +$8k–$20k).
• Vehicle data licensing: $2.5k–$15k/yr (SEMA Data Coop OR TecDoc), $5k–$25k/yr if both. Budget for it — this is the single biggest ongoing cost after hosting.
• Timeline: 12–20 weeks for a typical mid-market auto-parts store. Faster (8–10 weeks) if SKU count is small (<5k) and design is preserved. Longer (24–32 weeks) for B2B fleet + multi-region + EDI to suppliers in scope.
• Hosting: $500–$2,000/mo on Cloudways / Adobe Commerce Cloud. Auto parts catalog is heavy (image + spec data); over-provision for B2B trade-account peak load (Monday morning fleet reorders are predictable spikes).
• Ongoing: $2k–$8k/mo retainer for vehicle-data refresh handling, fitment-gap remediation, fleet onboarding, supplier EDI maintenance.

Risks specific to auto-parts migration:

• Fitment data quality — 90% of post-launch returns trace to bad fitment data. Budget time for QA on the top 1,000 SKUs by sales volume before going live. Test 50 (vehicle, part) pairs per category against expected fitment.
• OEM number normalization — suppliers format OEM numbers inconsistently (with/without dashes, leading zeros, alpha-prefix variations). Normalization rules need to live in PIM, not Magento, or you get duplicate cross-references.
• SEO redirects — URL structure typically changes (RevolutionParts URLs are very different from Magento). Vehicle landing pages (e.g. “2018 Honda Civic Parts”) need explicit redirects or you drop 30–50% of organic for ~8 weeks.
• B2B account migration — trade pricing, Net-30 limits, account-rep assignments, saved parts lists. Map cleanly or you alienate top customers.

Run the new store in parallel for 30 days behind feature flag, only flip DNS once 50 fitment scenarios pass + 30 successful test orders + 5 friendly trade customers complete a B2B order end-to-end. Auto-parts migrations done well don’t lose ranking; done badly they take a quarter to recover.