You should both agree exactly what is to be done and put it in writing. They should bundle all the software and instructions in a 3 ring binder with a number for support. If training is required, it should be included in the package. If you're already are on the net and familiar with procedures, you should have lower costs. Creating Web pages, like writing copy, is easy.
Successful ones take more time.
Others quote much higher rates. Your web designer should include registration on more than a dozen Web Indexes, a choice of background colors and the ability to scan in color pictures. You and the designer can work together at different locations to refine the page. Constant tinkering with graphics and copy is a natural inclination. You'll run up the cost unnecessarily.