I'm a freelance developer working mostly in Drupal the past 3 years. At times I have the need for a designer. I have not run across the need yet for a complete theme, but have needed (1) a complete design done in the form of a .psd using an existing base theme, where I provide a reasonable idea of what should be on the page and any information about existing elements and client preferences, (2) the same but beginning with already-existing wire frames, or (3) the need to create page designs for new pages to an existing site.
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.
