The verdict in three sentences
A B2B building materials marketplace linking 80 merchants and 3,000 tradespeople costs 60,000 to 140,000 EUR excl. VAT to build, depending on how deeply it integrates with merchant stock and the credit module. The model relies on a 3 to 6% commission on an average basket of 1,800 EUR, which demands volume: you need about 900 orders per month to cover a team of four. The decisive factor is 30-day payment terms through a factoring partner, without which tradespeople keep buying at the counter on their usual account.
The development budget in 2026
A construction B2B marketplace differs from an online shop through three expensive modules: multi-vendor management (catalogues, stock and delivery zones per merchant), trade credit, and job-site logistics (on-site delivery, time slots, crane or tail lift).
| Module | MVP | Full version |
|---|---|---|
| Scoping, design and tradesperson journey | 8,000 EUR | 15,000 EUR |
| Multi-vendor catalogue and price list import | 12,000 EUR | 25,000 EUR |
| Price, availability and lead time comparison by merchant | 6,000 EUR | 15,000 EUR |
| Payment, split and payouts to merchants | 10,000 EUR | 20,000 EUR |
| 30-day terms via factoring (partner API) | 8,000 EUR | 18,000 EUR |
| Job-site delivery, slots and tracking | 6,000 EUR | 17,000 EUR |
| Merchant back office and administration | 10,000 EUR | 30,000 EUR |
| Indicative total (excl. VAT) | 60,000 EUR | 140,000 EUR |
These figures are 2026 orders of magnitude. Recurring costs include hosting (300 to 900 EUR per month), maintenance (1,500 to 3,500 EUR per month) and marketplace payment provider fees, often 0.3 to 1.4% of volume depending on the card and SEPA transfer mix.
Which business model to choose
Commission alone is rarely enough in building materials, where merchant gross margins sit around 20 to 30%. The platforms that last combine several revenue streams.
| Revenue stream | 2026 range | Advantage | Limit |
|---|---|---|---|
| Transaction commission | 3 to 6% of basket | Aligns the platform with volume | Large merchants push to lower it |
| Merchant subscription | 150 to 600 EUR per month | Predictable revenue | Deters smaller players |
| Margin on 30-day terms | 0.5 to 1.5% of financed basket | Pays for a real service | Depends on credit risk |
| Featured listings and ads | 200 to 1,500 EUR per campaign | High margin | Only useful above 2,000 active buyers |
| Job-site delivery fees | 35 to 120 EUR per delivery | Covers logistics | Competes with merchants' own rounds |
| Premium tradesperson plan | 19 to 49 EUR per month | Builds loyalty | Low conversion at first |
The 30-day payment option is the real product. A factoring or B2B BNPL partner pays the merchant on D+2, carries the risk on the tradesperson after scoring and charges 1 to 2.5% of the financed amount. The platform can absorb part of this cost in its commission or pass it on.
The three risks to budget for
The first is disintermediation: after two orders, tradesperson and merchant are tempted to deal directly. Deferred payment, centralised invoices and job-site history are the best defences. The second is data quality: merchant catalogues often hold 15,000 to 40,000 references with inconsistent labels, and cleanup can take 2 to 3 months. The third is tradesperson acquisition: expect 40 to 90 EUR per active tradesperson through trade fairs, buying groups and field prospecting.
Mini case study
Need a professional website?
Kolonell builds websites that attract clients, optimized for the Sénégalese market. Free quote in 2 minutes.
Thomas Mercier, founder of a building materials marketplace around Lyon, is targeting month 18. At that point, 900 monthly orders at 1,800 EUR generate 1,620,000 EUR of volume. With an average 4% commission, gross revenue reaches 64,800 EUR per month. 60% of baskets use 30-day terms, and the platform covers 1.2% of those amounts, or 11,664 EUR. Net revenue is therefore about 53,100 EUR. On the cost side: team of four 32,000 EUR, marketing 12,000 EUR, payment fees 5,000 EUR, hosting and maintenance 4,000 EUR, for a total of 53,000 EUR. Break-even is reached, after an initial investment of 110,000 EUR excl. VAT and about 400,000 EUR of cumulative losses over 17 months.
FAQ
Do we need a licence to collect funds on behalf of merchants?
Yes, collecting and paying out funds on behalf of third parties is a regulated payment service. The usual solution is a licensed provider (Stripe Connect, Mangopay, Lemonway) that manages e-money accounts, for 0.3 to 1.4% of volume.
How many merchants are needed at launch?
Around twenty merchants spread across a 50 km area cover 80% of a tradesperson's everyday needs. Targeting 80 merchants from day one extends onboarding by 3 to 6 months.
Are 30-day terms expensive for the platform?
The partner usually charges 1 to 2.5% of the financed amount, depending on the risk profile. On a 1,800 EUR basket, that is 18 to 45 EUR, compared with a commission of 54 to 108 EUR.
Can we start without custom development?
SaaS marketplace solutions exist at 500 to 2,500 EUR per month, but they handle per-tradesperson negotiated prices and job-site delivery poorly. They work for testing a segment for 6 months before rebuilding.
How long to launch an MVP?
Allow 4 to 5 months for a 60,000 EUR MVP, including 6 weeks of catalogue cleanup. The full version takes 8 to 10 months.
Let's scope your project. Share your region, the number of committed merchants and your commission model: we will price an MVP between 60,000 and 140,000 EUR excl. VAT with a 4 to 10 month plan. 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.
