Most quotes come down to three things. Scope is the obvious one — page count, and more importantly how many of those pages are genuinely different from each other rather than the same template with different content.
Integrations are the one clients underestimate. Connecting a site to a payment provider, a CRM, an inventory system or a booking platform is where the unpredictable hours live, because the work depends on the quality of somebody else's API rather than on anything we control.
Content readiness moves timelines more than budgets, but it moves both. A project where copy, photography and product data are approved and waiting runs noticeably faster than one where the site is built and then waits weeks for text. If you need us to write the content, that is quoted as part of the work rather than assumed.
What does not change the price: asking for revisions within an agreed round, wanting the site to be fast, or expecting it to work properly on a phone. Performance and responsive design are part of building a site, not upgrades.