What changes the budget most
The biggest factor is scope. A small presentation site, a multilingual B2B site, and a website with admin workflows are not in the same workload range.
The second major factor is content depth. If the delivery also includes structure, FAQ, SEO basics, and lead path thinking, the work is more strategic than only coding screens.
Page count and template complexity
Multilingual support and SEO foundations
Forms, admin features, integrations, and permissions
Deployment, maintenance, and later iteration support