If it's plain HTML (or XHTML) + CSS, I doubt you can charge a
lot for it. It's very easy to create them. Or just download some
templates off the web and use an editor to create another
page.
However, if you are creating a dynamic webpage, say using PHP or
JSP, then it's another issue. Depending on your skills, how you use
the scripting languages to create a page, you can earn quite a lot
from it, either as a flat fee or on hourly basis.
Add some creative elements to it, pay is even more.