I just picked up a Mio DigiWalker C310x GPS, and I am very impressed with it so far. Mio's new models are coming out so they are having a fire sale on this unit. I picked mine up from Circuit City for $199, but I have seen it as cheap as $159 at Comp USA. This unit has a built-in MP3 player and will support up to 4 gig memory cards. I have already unlocked the system to act as a full blown PDA, and I'm in the process of creating custom menus that will be easily accessible while moving. I have included a screenshot of the first menu page that I have created. I still have 2 more pages to create and I should have it just the way I want it.
Here is a link for anyone that's interested.
http://www.miogps.com/US/products_c310xfeatures.htm
Screenshot Icons:
Top Row: GPS Software, GPS Settings, Unlock Tool, Movie Player
Next Row: Photo Viewer, Calculator, MP3 Player, and Next Page