fstep,

Fees based on a "per page" or "per hour" ratio are difficult to maintain.

Bundled price points would suit your situation better. For example, let's say you provide a homepage, two sub-pages, and validated markup, for a $150 base payment. Depending on special requests by the client, you could provide each sequential sub-page for a base of $25, and any extra features for an additional $10 or so, depending on what the client actually needs.

If you need anymore help, feel free to contact me, and we'll definately talk more.