I have seen in the past that most of the clients I work have a comfort level of $250/page, though some would just then have the home page designed and based the rest of the site on it. These have typically been business sites (see my portfolio) and not media, entertainment or personal promo ... so without multimedia bells and whistles.

If you are interested in exploring an association, flexible in your process, able to design from varying abstraction levels of description, please contact me off list and provide a link to some designs you have done for Drupal and e-commerce sites.