The verdict in three sentences
A custom B2B client portal becomes economically justified above roughly 40 active accounts or as soon as an ERP connector is central to the workflow. Below that, a packaged SaaS stays cheaper over three years despite its customization limits. The right question isn't the build price but the 36-month TCO: build + maintenance + hosting + the cost of not being able to customize.
Initial build: what a custom portal covers
A typical B2B client portal bundles order tracking, invoice access, a document space and support ticketing. The 2026 estimate depends mainly on the number of modules and how deeply it integrates with your systems.
| Scope | Initial build (EUR) | Timeline |
|---|---|---|
| MVP (auth, roles, order tracking) | 28,000 - 36,000 | 8-10 wks |
| Standard (+ invoices, docs, tickets) | 38,000 - 48,000 | 10-12 wks |
| Extended (+ ERP connector, alerts) | 48,000 - 55,000 | 12-16 wks |
| Developer day rate | 480 - 620 EUR | — |
The ranges assume a modern stack (SSR framework, managed database, role-based auth). A real-time ERP connector alone adds 8,000 to 16,000 EUR depending on the available API.
The 3-year TCO: build vs buy
This is where the decision is settled. Application maintenance runs 18-22% of the build per year; managed hosting, 90 to 260 EUR/month depending on load.
| Line item (36 months) | Custom | SaaS, 20 users |
|---|---|---|
| Build / setup | 28,000 - 55,000 | 3,000 - 8,000 |
| Subscription | 0 | 24,000 - 38,000 |
| Maintenance / evolutions | 15,000 - 24,000 | included |
| Hosting, 3 years | 3,200 - 9,400 | included |
| Customization | included | 4,000 - 6,000 (add-ons) |
| 3-year TCO | 48,000 - 85,000 | 34,000 - 52,000 |
Below 20-30 accounts, SaaS almost always wins. Above ~40 active accounts, per-user SaaS fees and add-ons catch up and then overtake the custom TCO, which stays fixed.
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Mini case study
Mark, COO of an industrial SME in London (technical supplies, 46 key accounts) is weighing options. The chosen SaaS costs 158 EUR/user/year for 25 accounts, i.e. 3,950 EUR/year plus 5,000 EUR of add-ons over three years: TCO ≈ 16,850 EUR. But he's targeting 60 accounts within 18 months: at that volume the SaaS climbs to ~9,500 EUR/year. Custom at 42,000 EUR build + 22,000 EUR maintenance/hosting over three years (64,000 EUR) becomes competitive once he passes 40 accounts and gives him the ERP connector the SaaS charges as an option. He picks the build, amortized over 3.5 years.
FAQ
What's the minimum budget for a real B2B client portal? Expect at least 28,000 EUR for a credible MVP (role-based auth, order tracking, invoices). Below that you get a mockup, not a production tool.
Is maintenance really mandatory? Yes, roughly 18-22% of the build per year. It covers security, version upgrades, fixes and small evolutions; without it, technical debt explodes within 18 months.
At how many accounts does custom become worthwhile? The 2026 tipping point is around 40 active accounts, earlier if an ERP connector or specific business logic is essential.
How long for an MVP? 8 to 12 weeks for standard scope, provided your system APIs and pricing rules are documented at kickoff.
Can we start small and expand? Yes, it's actually recommended. A 30,000 EUR MVP then quarterly increments smooth cash flow and validate usage before investing in ERP integration.
Let's scope your project. Tell us your account count, priority modules and target systems, and we'll price the build plus 3-year TCO. 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.
