The verdict in three sentences
For a multi-warehouse B2B distributor, a custom ERP (EUR 80,000-220,000) is justified when your client pricing, stock rules and EDI become too specific for a packaged vendor. Odoo remains unbeatable for a fast, cheap start, but it slows you down as business quirks pile up. The real ROI shows in the 20-35% reduction in stockouts and pricing automation, not in the license price.
Custom, Odoo or vertical vendor?
Three paths, three risk profiles. Odoo (open source) is cheap and modular but needs customizations that make upgrades heavier. The vertical vendor knows your trade but imposes its processes. Custom fits your exact rules at the cost of a heavier upfront investment.
| Criterion | Custom | Odoo (integrator) | Vertical vendor |
|---|---|---|---|
| Project budget | EUR 80,000-220,000 | EUR 25,000-80,000 | EUR 40,000-120,000 |
| Timeline | 7-12 months | 3-6 months | 4-8 months |
| Per-client pricing | Unlimited | Medium | Module-dependent |
| Advanced multi-warehouse | Fully custom | Good | Good |
| EDI integration | Native | Add-on | Often included |
| Upgrade cost | Controlled | Regression risk | Included but rigid |
| Code ownership | Yes | Partial | No |
| Annual maintenance | 15% of build | 12-18% | 18-22% (license) |
3-year TCO and stock impact
Same scope (multi-warehouse stock, client pricing, orders, invoicing, EDI), here is the 2026 order of magnitude for a 45-employee, 3-warehouse distributor.
| Line item | Custom | Odoo | Vertical vendor |
|---|---|---|---|
| Initial build / integration | EUR 150,000 | EUR 55,000 | EUR 85,000 |
| Licenses / yr | EUR 0 | EUR 9,000 | EUR 22,000 |
| Hosting + monitoring / yr | EUR 9,600 | EUR 6,000 | included |
| Maintenance / yr | EUR 22,500 | EUR 9,000 | included |
| 3-year total | EUR 246,300 | EUR 127,000 | EUR 151,000 |
Custom is the most expensive to buy, but it is the only one that fully removes the pricing and stock friction that costs money every day. The question isn't TCO alone but the cost of stockouts and pricing errors it eliminates.
Mini case study
Claire, CFO of an industrial-supplies distributor in Lille, does EUR 18M revenue across 3 warehouses. Her stockout rate is 6%, each stockout costing an average of EUR 140 lost margin on ~9,000 affected lines/month, i.e. ~540 stocked-out lines = EUR 75,600/month of margin at risk (about 25% permanently lost = ~EUR 19,000/month). A custom ERP cutting stockouts from 6% to 4% recovers a third of that loss, ~EUR 6,300/month (EUR 75,600/year). Add pricing automation (2 FTEs lightened by 30%) and amortizing a EUR 150,000 build over 4 years becomes sustainable from year two.
FAQ
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When does custom ERP beat Odoo?
When Odoo customizations exceed 40-50% of the need: at that point every upgrade becomes risky and custom becomes competitive over time again.
How much does EDI integration cost?
Expect EUR 12,000-35,000 depending on the number of partners and message types (orders, dispatch advices, invoices). It's native in custom; in Odoo it's an add-on to harden.
What real gain on stockouts?
A 20-35% reduction is realistic with well-tuned reorder rules and per-warehouse thresholds. On an average distributor that is often EUR 60,000-120,000/year of margin preserved.
Is the 7-12 month timeline unavoidable?
Shorten it by shipping modules: stock and orders first (4-5 months), then pricing, EDI and invoicing. You create value before the project ends.
Can we migrate from a legacy tool?
Yes, data migration (items, clients, prices, history) is 8-15% of the budget and must be scoped from the start.
Let's scope your project. Tell us your number of warehouses, your order-line volume and your pricing quirks: we'll frame an ERP delivered by modules, indicative budget EUR 80,000-200,000. 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.
