Typical ranges
| Project | Range | Duration |
|---|---|---|
| Small internal tool, one workflow | £6,000–£12,000 | 5–8 weeks |
| Business application, several workflows | £15,000–£40,000 | 10–18 weeks |
| Customer portal on existing data | £10,000–£25,000 | 8–14 weeks |
| Integration middleware | £8,000–£20,000 | 6–12 weeks |
| Legacy modernisation | £10,000–£50,000 | Ongoing |
Ranges are wide because the same description covers very different amounts of work depending on what the system has to talk to.
What actually moves the price
- Integrations — each system you must connect to, and whether it has an API
- Business rule complexity — pricing, approvals, calculations with exceptions
- Data migration from whatever you use now
- Permission complexity — who can see and do what
- Reporting, which is frequently underestimated
Screen count is a poor proxy for effort. Twenty similar screens is a template; one screen implementing eight interacting pricing rules is a fortnight.
What should be included
- Tests around the important logic
- A deployment process, not FTP
- Documentation sufficient for another developer
- Handover and training
- The code, in a repository you own
A quote missing those is quoting less than a maintainable system, and the difference arrives later as cost.
Running and maintenance
Hosting for a typical business application is £30–£200 a month. Maintenance is 15–25% of build cost annually, covering dependency updates, security patching and small changes.
Budget the maintenance explicitly. An unmaintained application becomes progressively more expensive to change, which is how businesses end up needing a rewrite.
Cheap quotes are usually incomplete
The gap between quotes is nearly always scope: tests, deployment, documentation, edge cases and the integrations nobody discussed.
Ask each supplier specifically what is not included. That question narrows most comparisons considerably.