The verdict in three sentences
A custom B2B booking platform is budgeted in London between 30,000 and 75,000 EUR in 2026, real-time calendar and online payment included. The deciding factor is business-rule complexity: cross availability, multiple resources, conditional pricing. If your rules are simple, a SaaS block is enough; if they're specific, custom avoids costly workarounds, in 4 to 7 months.
Budget for a custom booking platform
Price depends on the number of resources and the granularity of availability rules. 2026 ranges (order of magnitude).
| Module | 2026 range (EUR) | Timeline |
|---|---|---|
| Real-time multi-resource calendar | 10,000 - 20,000 | 5-7 weeks |
| Business rules engine | 8,000 - 18,000 | 4-6 weeks |
| Online payment + deposits | 5,000 - 10,000 | 3-4 weeks |
| Resource management + roles | 6,000 - 15,000 | 4-6 weeks |
| Notifications + reminders | 3,000 - 7,000 | 2-3 weeks |
| Dashboard + reporting | 5,000 - 12,000 | 3-4 weeks |
Maintenance of a transactional platform is higher than a brochure site because it handles money and real-time slots.
| Recurring item | 2026 cost (EUR/month) |
|---|---|
| Maintenance + supervision | 800 - 2,000 |
| Hosting + real-time database | 120 - 400 |
| Payment fees | ~1.5 % + 0.25 EUR/transaction |
| SMS/email notifications | 40 - 150 |
| Minor evolutions | 300 - 900 |
SaaS booking block vs custom
SaaS tools (Calendly, SimplyBook) cover simple booking for 30 to 120 EUR/month. They break down as soon as your business rules go beyond standard: combined-resource booking, dynamic pricing, per-client B2B quotas.
| Criterion | SaaS block | Custom |
|---|---|---|
| Initial cost | 0 - 3,000 EUR | 30,000 - 75,000 EUR |
| Monthly cost | 30 - 120 EUR | 800 - 2,000 EUR |
| Complex business rules | no | yes |
| Cross multi-resource | limited | full |
| Own brand and UX | limited | total |
| Custom integrations | rare | unlimited |
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Mini case study
Julien, director of a training-studio network in London, manages 12 rooms and 40 trainers with cross availability rules. His custom platform costs 52,000 EUR, maintenance 1,200 EUR/month. Previously, two assistants spent 3 h/day coordinating bookings by phone, about 4,500 EUR/month. The platform automates 70 % of that coordination, i.e. 3,150 EUR/month saved: the investment pays back in about 20 months.
FAQ
When is a SaaS block enough? If you manage a single resource and fixed slots, a 30-120 EUR/month SaaS is perfect. Custom becomes justified from several cross resources or conditional pricing onward.
Is online payment mandatory? For B2B, a deposit at booking sharply reduces cancellations. Integration costs 5,000 to 10,000 EUR and pays off fast through fewer no-shows.
How long is development? Budget 4 to 7 months depending on rule complexity. The real-time calendar and the rules engine account for half the timeline.
What maintenance should I plan? A transactional platform requires 800 to 2,000 EUR/month: it handles money and critical slots, and downtime costs dearly in lost bookings.
Can I start simple then enrich? Yes: ship the calendar and payment first (30,000-45,000 EUR), then add the advanced rules engine when volume justifies it.
Let's scope your project. Describe your resources, availability rules and budget, and we'll frame your booking platform. 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.
