The verdict in three sentences
A vertical SaaS is fast to deploy but locks you in: annual price hikes, high exit cost and throttled data export. A custom build demands £35,000 to £80,000 upfront but turns a rising subscription into an asset you own, with a fixed, predictable support fee. The real calculation runs over 5 years and includes the acquisition or end-of-life risk of the vendor.
The real cost of leaving a SaaS
Leaving a vertical SaaS is never free: you must extract data, clean it, remap it and rebuild integrations. Many vendors bill for export beyond a raw dump.
| Exit line item (2026 order of magnitude) | Range |
|---|---|
| Export / data unlock fees | £450–3,500 |
| Data migration and cleanup | £3,500–13,000 |
| Rebuilding integrations | £2,600–8,700 |
| Training on the new tool | £1,700–7,000 |
| Dual subscription during transition | £1,300–5,200 |
| Total exit cost | £7,000–26,000 |
Five-year pricing projection
Assumption: starting SaaS subscription £1,600/month for 30 users, average 12 %/year increase. Against it, a custom build at £62,000 amortised, support £700/month, hosting £100/month.
| Year | Vertical SaaS (12 %/yr) | Custom (support + amortised build) |
|---|---|---|
| 1 | £19,200 | £62,000 + £9,600 = £71,600 |
| 2 | £21,504 | £9,600 |
| 3 | £24,084 | £9,600 |
| 4 | £26,974 | £9,600 |
| 5 | £30,211 | £9,600 |
| 5-year total | £121,973 | £110,000 |
From year 4, cumulative custom drops below the SaaS, and the gap widens mechanically afterwards because the subscription keeps climbing while support stays flat.
Ownership vs subscription: beyond price
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| Criterion | Vertical SaaS | Custom build |
|---|---|---|
| Code ownership | no | yes (balance-sheet asset) |
| Control over increases | imposed (10–15 %/yr) | controlled (negotiated support) |
| End-of-life / acquisition risk | high | none |
| Data portability | limited | full |
| Deployment speed | 1–4 weeks | 8–16 weeks |
| Fine process fit | throttled | unlimited |
Mini case study
James, operations director of a services SME in London, pays £1,600/month for a vertical SaaS covering 30 users. His vendor announced +14 % for 2026 and has been acquired by a fund. Over 5 years he projects £122,000 of rising subscriptions, plus a forced-migration risk billed at £18,000. A custom build is quoted at £62,000 + £700/month support, i.e. £110,000 over 5 years, with code he owns. He greenlights the build: beyond the £12,000 saving, he removes the acquisition risk and regains full control of his data and roadmap.
FAQ
Can a vertical SaaS really block my data export? Rarely fully, but a clean export (usable formats, full history, attachments) is often billed £450–3,500 and deliberately incomplete, inflating migration cost.
What price increase should I anticipate? Across 2024-2026, B2B vertical SaaS rose 10 to 15 %/year on average. A contractual indexation cap can limit this risk: negotiate before signing.
How much does a replacement build really cost? Between £35,000 and £80,000 depending on scope, plus £400–1,050/month support. Payback usually lands between year 3 and year 4.
Doesn't custom also create dependency on the developer? The risk exists but stays low if code, documentation and access are handed over: you can switch maintainers, which is impossible with a proprietary SaaS.
What if my vendor gets acquired? Check your reversibility clauses, immediately export a full backup, and price a custom plan B before any imposed increase.
Let's scope your project. Send us your current subscription, user count and exit clauses: we project your 5-year dependency cost and price a replacement build (from £35,000). 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.
