One like this is probably the go Pud.
High res (800 x 480) 7" screen, road nav comes with it, bluetooth, already unlocked and running Windows CE, and lots of stuff for $280 delivered (to me). Add OziExplorerCE for $40 and some maps for about $50 - about $400 posted to you after I set it up.
You'll probably want the PC version of OziExplorer for planning and creating routes and waypoints - add $130.
Because this one is already unlocked, you can probably do it yourself, although I'm happy to do it for you - that would give me a chance to see how these new ones are.
Let me know.