Two things >> volume and customization.
Volume is simply the # of pages on your site. All things being equal, a 10-page website is going to be less expensive to develop than a 95-page site.
Customization can apply to numerous aspects of a web development project. For example …
- Custom content. Do you already have written content for your site or does it have to be developed from scratch? Is your existing content kind of “rough”, needing a lot of editing and refinement?
- Custom design. Are you wanting a highly unique or unusual layout for your site that’ll require modification to the standard site architecture of the theme we are using to develop your site?
- Custom images and graphics. Do your images and graphics require specialized Photoshop effects, above and beyond standard cropping and resizing?
- Custom programming. Does your site require integration and rigorous testing with a 3rd-party application like a shopping cart or client scheduling system?
It’s totally fine if you want a high degree of customization for your site. Just know that it will increase the overall cost of your project.