The verdict in three sentences
The 3-year total cost (TCO) of a B2B e-commerce platform in Berlin sits, in 2026, between 100,000 and 250,000 EUR depending on the chosen model. The build price or SaaS subscription is only the visible part: ERP integration, transaction fees, maintenance, hosting and evolutions often make up more than half the bill. At high volume, transaction fees (0.5 to 2%) and maintenance (10 to 15%/year) are the items that tip the decision between SaaS and custom.
3-year TCO: custom vs SaaS
| Item | Custom (EUR) | SaaS (EUR) |
|---|---|---|
| Build / subscription | 40,000-100,000 (build) | 2,300 EUR/mo = 82,800 over 3 yrs |
| ERP integration | 15,000-35,000 | 15,000-40,000 |
| Transaction fees | 0 (excl. PSP) | 0.5-2% of online revenue |
| Maintenance / evolutions | 12,000-30,000/yr | Partly included + apps |
| Hosting / infra | 3,600-14,400 over 3 yrs | Included |
| 3-year total | ~110,000-230,000 | ~120,000-250,000+ |
SaaS looks cheaper up front but transaction fees and apps catch up at high volume; custom has a higher initial capex but a low marginal cost.
Weight of transaction fees by volume
| Annual online revenue | Fees at 1% (SaaS) | Fees at 1% over 3 yrs |
|---|---|---|
| 500,000 EUR | 5,000 EUR/yr | 15,000 EUR |
| 1,000,000 EUR | 10,000 EUR/yr | 30,000 EUR |
| 2,000,000 EUR | 20,000 EUR/yr | 60,000 EUR |
| 3,500,000 EUR | 35,000 EUR/yr | 105,000 EUR |
| 5,000,000 EUR | 50,000 EUR/yr | 150,000 EUR |
This table explains why, above ~2M EUR of online revenue, custom often becomes cheaper over 3 years despite its higher capex.
Mini case study
Claire, CFO of an industrial distributor in Berlin, targets 2.5M EUR of online revenue. On SaaS: subscription 82,800 EUR + integration 30,000 EUR + transaction fees at 1% (75,000 EUR over 3 yrs) + apps 18,000 EUR = ~205,800 EUR over 3 years. On custom: build 88,000 EUR + integration 25,000 EUR + maintenance 15,000 EUR/yr (45,000 EUR) + hosting 9,000 EUR = ~167,000 EUR over 3 years. The ~39,000 EUR gap in favour of custom, plus code ownership, settles her decision at this volume.
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What is the realistic 3-year TCO of a B2B e-commerce in Berlin?
Between 100,000 and 250,000 EUR depending on model and volume. Custom starts from a higher capex but low marginal cost; SaaS spreads cost but adds transaction fees and apps.
Which items are most often forgotten?
Transaction fees, maintenance (10-15%/year of build), SaaS apps, hosting and evolutions. They often make up more than half the TCO.
At what volume does custom win over 3 years?
Generally above 2M EUR of annual online revenue, when cumulative transaction fees exceed the initial capex gap.
How to reduce maintenance?
Clean, documented and tested code lowers maintenance. Keep an evolutions budget separate from fixes so you do not confuse maintenance with roadmap.
Should we think in capex or opex?
Both: SaaS favours opex (monthly), custom favours capex (investment). The choice depends on your volume, cash position and horizon.
Let's scope your project. Share your target online revenue and your ERP: we build your 3-year TCO for SaaS vs custom, budget 100,000-250,000 EUR. 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.