4 Page Wordpress Site

It can vary based on the project's specific requirements. It involves complex layouts, animations, or custom functionality.
As above!

It depends on what is really involved. Things to be factored could be : how much content is on the pages, illustration, graphics, copy, interaction, forms, call to action, UI design brand integration. It can vary drastically depending on the stuff that is on the 4 pages.

A 4 page website with a couple of sentences that is very thin and weak on content and marketing will be cheaper than one that isn't. And some companies won't know the differences between the 2. There are websites and then there are websites.