Cost + timeline for a serious B2B Magento implementation?

Real ranges from 40+ shipped projects:

Greenfield Magento Open Source B2B (no migration):

• Timeline: 12–16 weeks build + 4 weeks stabilisation
• Build cost: $30k–$80k depending on segment-pricing complexity + ERP integration depth
• Extensions: $3k–$8k one-time (Companies, Quote Workflow, Subscriptions, etc.)
• Hyvä theme licence: $1,000 one-time
• Hosting: $400–$1,500/mo (Cloudways / dedicated)
• 3-year TCO: $80k–$200k

Migration from Shopify Plus / SAP Hybris / custom portal:

• Timeline: 16–24 weeks build + 4 weeks parallel run + 4 weeks stabilisation
• Build cost: $50k–$140k
• Data migration: $10k–$30k (companies, buyers, pricing, AR balances)
• ERP re-integration: $15k–$50k depending on system
• 3-year TCO: $130k–$320k

Adobe Commerce B2B (vendor-supported):

• Same build cost as Open Source + Adobe Commerce license $30k–$80k/yr based on GMV
• 3-year licence: $90k–$240k on top of build cost
• Pays for itself when (a) you’d need 24/7 SLA anyway, or (b) you’re >$10M GMV with full B2B usage

Below $5M B2B GMV: Open Source + extensions is the right call. $5–$10M: close call — depends on team. Above $10M: Adobe Commerce + Cloud often wins on operational cost despite the licence.

Cheapest B2B build that’s not a regret: $30k. Anything cheaper skips ERP integration or quote workflow and you’ll rebuild within 18 months. The honest floor.