The biggest cost driver is rarely the technology stack — it remains how much is still undecided. Each unanswered question in the brief becomes a contingency inside the number you receive. A team that does not know what happens on the unhappy path will assume the more expensive option. Putting two weeks into a proper discovery often reduces the final cost much more than haggling over hourly rates.
Third-party integrations tend to be another reliable source of cost. A form that saves data is low risk; the same feature talking to an old accounting system is a different problem. The unknown sits in the counterparty: undocumented APIs, long certification processes, java development agency inconsistent data. Ask any vendor to price integrations separately, because this is where estimates break.
The requirements nobody writes down silently change the budget. An application used by a handful of staff costs far less than the same idea handling public traffic. Audit and compliance requirements, availability guarantees, performance under load, traceability and multi-language support each add real engineering time. Put them in the brief or you can expect them to arrive later as change requests.
The mix of people behind the number changes the arithmetic. A rate card reveals very little on its own: a senior engineer at twice the price frequently turns out to be less expensive in the end than a pair of junior developers who require heavy code review. Also ask what else appears on the invoice: delivery management, testing, release engineering and design are legitimate costs, but these should be visible in the estimate.
The build price is laravel better than wordpress rarely the full cost of ownership. Budget for hosting, subscriptions and licences, observability and an ongoing support budget each year. A common working assumption is that a live system requires a meaningful share of the initial investment every year simply to stay current. Treating the launch as the finish line is the classic mistake.