The biggest cost driver is rarely the choice of framework — it remains how much is still undecided. Every open question in the requirements becomes a contingency somewhere in the quote. A vendor that cannot see what happens on the unhappy path will assume a pessimistic case. Spending a week articles on software outsourcing a proper discovery can cut the overall figure far more than any rate negotiation.
Integrations tend to be the next major multiplier. A feature that touches only your own data is low risk; the same functionality talking to a payment aso service provider and a CRM is a different problem. The effort lives in the third party: poor documentation, slow approval cycles, fields that mean something different on each side. Ask any vendor to price integrations separately, since this is where estimates break.
The requirements nobody writes down quietly rewrite the number. An application used by a handful of staff has almost nothing in common with the same functionality serving a hundred thousand users. Compliance work, high availability, performance under load, data retention rules and next.js vs laravel multi-language support add weeks of work. State them early or else expect the estimate to move later.
The mix of people behind the number matters a great deal. An hourly rate reveals very little on its own: an experienced engineer at a higher rate can be less expensive in the end than two inexperienced developers who need constant review. Check too who else is billed: project management, testing, DevOps and UX design have to be done by someone, but they should be itemised.
The build price is not what you will actually spend. Budget for cloud costs, paid APIs, observability and a change budget for every year the real estate software development runs. A reasonable rule of thumb holds that software in active use consumes a meaningful share of the initial investment per year in fixes, updates and small changes. Ignoring this remains the classic mistake.