The verdict in three sentences
The build vs buy decision isn't made on gut feel but on five-year TCO and firm strategy. A vertical vendor costs EUR 40-120 per user per month — a subscription that grows with headcount — while custom is a one-off investment of EUR 40,000-90,000 plus controlled maintenance. Above 12 to 18 staff, or as soon as you want to avoid lock-in, custom almost always wins over time.
The break-even point, size by size
The tipping point depends on the vendor's per-user price and the firm's size. The higher the headcount, the more the per-seat subscription penalises SaaS against a near-fixed custom cost.
| Headcount | SaaS cost/year (EUR 60/user) | Custom amortised/year* | Decision |
|---|---|---|---|
| 5 staff | EUR 3,600 | EUR 13,000 | SaaS |
| 10 staff | EUR 7,200 | EUR 14,000 | SaaS |
| 15 staff | EUR 10,800 | EUR 15,000 | Break-even |
| 25 staff | EUR 18,000 | EUR 16,000 | Custom |
| 40 staff | EUR 28,800 | EUR 18,000 | Custom |
*EUR 60,000 custom amortised over 5 years + average maintenance.
5-year TCO and compared risks
Beyond the sticker price, each option carries risk: lock-in and price hikes on the vendor side, provider dependency on the custom side. This table sets them head to head over five years for a 25-staff firm.
| Criterion | Vertical vendor | Custom |
|---|---|---|
| 5-year cost (25 users) | EUR 90,000-150,000 | 60,000 + 60,000 maint. = EUR 120,000 |
| Price hikes | 5-12%/year imposed | Controlled |
| Code ownership | None | Total |
| Customisation | Limited | Unlimited |
| Lock-in / migration | High | Low |
| Provider dependency | Low | Medium (mitigated by docs + delivered code) |
| Time to go live | 2-6 weeks | 4-9 months |
Mini case study
Mr Fenton, a partner in a 28-staff firm in Birmingham, pays a vertical vendor EUR 78 per user per month, i.e. EUR 26,208 per year — with an 8% rise announced for 2027. Over five years at a flat rate that's already EUR 131,040. A custom build at EUR 72,000 plus EUR 11,000 annual maintenance reaches EUR 127,000 over five years while removing the hike risk and giving him code ownership. Beyond year six, custom only costs maintenance, widening the gap every year.
FAQ
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When is custom the wrong choice?
Below 10 staff, or if your processes are very standard, a vertical vendor stays faster and cheaper. Custom is justified by size, workflow specificity or the will to avoid lock-in.
How do I limit provider dependency?
Require the source code, technical documentation, automated tests and a standard stack (no proprietary framework). You can then switch provider without starting over.
Can we blend both approaches?
Yes, it's common: keep the vendor for certified production and build custom for management, the portal and missing integrations.
What is the real hidden cost of SaaS?
Price hikes (5-12%/year), the cost per new user and migration difficulty. A firm that doubles headcount sees its SaaS bill mechanically double.
How long should a custom build take?
Allow 4 to 9 months depending on scope, shipping by modules to put value into production within the first weeks.
Let's scope your project. Give us your headcount, your current SaaS rate and your pain points: we'll build a costed 5-year TCO comparison and a custom perimeter. 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.
