The verdict in three sentences
For a London wholesaler or manufacturer, a B2B SaaS launches fast (800-3,000 EUR/month) but often bills a percentage of GMV that hurts once online sales pass 1M EUR. A custom platform costs 25,000-80,000 EUR to build but removes the commission and matches your business rules (per-customer pricing, volume discounts, credit terms). The right call depends on your annual volume and how complex your commercial terms are.
B2B SaaS vs custom: the 2026 budget comparison
The two models have very different cost structures. SaaS smooths spend but makes it recurring and revenue-indexed; custom front-loads the investment, then limits you to maintenance.
| Criterion | B2B SaaS | Custom build |
|---|---|---|
| Upfront cost | 3,000-8,000 EUR (setup) | 25,000-80,000 EUR |
| Recurring cost | 800-3,000 EUR/month | Maintenance 600-1,200 EUR/month |
| GMV commission | 0.3-1.5% | 0% |
| Time to launch | 4-8 weeks | 8-16 weeks |
| Business customisation | Limited to options | Full |
| Code ownership | No | Yes |
| Developer day rate | included | 500-700 EUR |
What a B2B platform must handle that B2C ignores
A B2C site shows one price; a B2B portal must orchestrate far richer rules. These functions account for most of the development budget.
| B2B function | Commercial impact | Dev complexity |
|---|---|---|
| Per-customer / group pricing | Retains key accounts | Medium |
| Volume discounts (tiers) | AOV +15-25% | Medium |
| Credit limit and terms | Protects cash flow | High |
| Quick order / reorder | Cuts ordering time | Low |
| Account-restricted catalogue | Controls reseller offer | Medium |
| ERP connector (stock, price) | Zero double entry | High |
| Card payment (1.4-2.5%) + transfer | 24/7 collection | Medium |
Mini case study
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Thomas runs a catering-supplies wholesaler in London, 3.2M EUR turnover, wanting to move 40% online (1.28M EUR GMV). On SaaS at 1,800 EUR/month plus 0.8% of GMV, he'd pay 21,600 EUR in subscription plus 10,240 EUR in commission, that is 31,840 EUR in year one, with a bill that rises as sales grow. Custom at 55,000 EUR plus 900 EUR/month maintenance (10,800 EUR/year) means 65,800 EUR in year one, but from year two his spend drops to 10,800 EUR versus over 32,000 EUR on SaaS. Break-even lands around 20 months: beyond that, custom is clearly more profitable at his volume.
FAQ
Is a B2B SaaS enough to start? Yes, if your GMV is under 500,000 EUR/year and your pricing rules are simple. The 0.3-1.5% commission stays bearable and you go live in 4-8 weeks.
At what volume does custom pay off? As a 2026 order of magnitude, from 1M EUR annual GMV with complex commercial terms, a 55,000 EUR build amortises in 18-24 months against SaaS commissions.
How much is the ERP connection? Budget 8,000-20,000 EUR depending on the ERP (SAP, Sage, Cegid) and number of flows (stock, price, orders, invoices). It's the most underestimated line item.
What payment fees should I expect? In 2026, a card costs 1.4-2.5% + 0.25 EUR per transaction, and a SEPA transfer about 0.25 EUR fixed. On high B2B baskets, transfer is far cheaper.
What's a realistic timeline for a custom platform? Between 8 and 16 weeks depending on catalogue, ERP and payment scope. An order-taking MVP can ship in 8-10 weeks.
Let's scope your project. Tell us your order volume, your ERP and your pricing rules, and we'll cost SaaS versus custom over three years. 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.