The verdict in three sentences
A custom B2B marketplace (vendor accounts, multi-supplier catalog, payment split, commissions) costs 40,000 to 150,000 EUR and takes 4 to 9 months to build. Turnkey solutions (Sharetribe, Mirakl, CS-Cart) launch faster but charge fixed fees plus 5 to 15% of GMV. Custom becomes profitable from a GMV of 500,000 EUR/year, because it removes the platform commission and creates an owned asset.
Custom vs turnkey solutions
SaaS marketplace solutions speed up launch but tax growth: the higher your volume, the heavier the platform commission. Custom flips the logic: a bigger upfront investment, then a near-zero marginal cost per transaction.
| Criterion | Custom | Mirakl / Sharetribe |
|---|---|---|
| Upfront cost (EUR) | 40,000 - 150,000 | 0 - 25,000 (setup) |
| Recurring fees | Hosting + maintenance | Subscription + 5-15% of GMV |
| Time to launch | 4 - 9 months | 6 - 12 weeks |
| Code ownership | Full (asset) | None (tenant) |
| Customization | Unlimited | Bounded by the platform |
| Marginal cost/transaction | ~0 | 5-15% of GMV for life |
What makes up the development budget
A B2B marketplace is not simple e-commerce: payment split, vendor management, and commissions are the real complexity. 2026 orders of magnitude (France):
| Module | Range (EUR) | Contents |
|---|---|---|
| Vendor accounts & onboarding | 8,000 - 18,000 | KYC, validation, profiles |
| Multi-vendor catalog | 10,000 - 25,000 | Import, moderation, search |
| Cart & payment split | 12,000 - 30,000 | Stripe Connect, payouts |
| Commission engine | 6,000 - 15,000 | Scales, invoices, statements |
| Admin + vendor dashboards | 8,000 - 20,000 | Analytics, dispute handling |
| Stripe Connect fees | 1.4 - 2.9% + 0.25 EUR | Per transaction, ongoing |
Add 15 to 20% of the budget in annual maintenance and a reserve for compliance (invoicing, VAT, B2B legal notices).
Mini case study
Karim, founder of an industrial-supplies marketplace in Lyon, targets 1,200,000 EUR of GMV in year one. On Mirakl, with an 8% platform commission, he would pay 96,000 EUR/year in commissions, plus the subscription.
Custom, he invests 95,000 EUR for a complete platform (vendors, Stripe Connect split, commissions) delivered in 7 months. His only variable costs become Stripe fees (~1.7%, i.e. ~20,400 EUR/year) and hosting/maintenance (~18,000 EUR/year). In year one he saves ~96,000 - 38,400 = ~57,600 EUR versus the commissioned model, and the gap widens every year as GMV grows. The platform becomes a resellable asset.
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FAQ
From what GMV is custom justified?
Beyond 500,000 EUR of GMV/year, the avoided platform commission (5 to 15%) exceeds the maintenance cost of custom. Below that, a SaaS solution stays safer.
How long to launch a B2B marketplace?
Expect 4 to 9 months depending on the number of modules. A focused MVP (vendors + catalog + payment) can ship in 4 to 5 months.
How to handle payment split legally?
Via a licensed provider like Stripe Connect or Mangopay, which handles fund splitting and vendor payouts in compliance with payment services regulation.
What commission to charge vendors?
In B2B, commissions often sit between 5 and 15% by category and vendor margin; some marketplaces add a monthly vendor subscription.
Can we start as an MVP then expand?
Yes, it is recommended: launch a vendors + payment core, validate the market, then add advanced commissions, analytics, and PWA in iterations.
Let's scope your project. Give us your target GMV, expected vendor count, and categories, and we quote a custom marketplace with payment split. Detailed quote within 48 h. WhatsApp +221 77 596 93 33.
Mohamed Bah
Fondateur, Kolonell
Passionate about digital and entrepreneurship in Africa, Mohamed has been helping Sénégalese businesses with their digital transformation since 2020. Founder of Kolonell, he believes every SME deserves a professional and accessible online présence.
