I am using the Pharos GPS Phone 600 - I believe it will be released in the next couple of weeks.

Price might be slightly out of your range, but it is also a windows Mobile 5 device, the phone is very good and the GPS software works like a champ. The overall footprint is pretty small, with a nice large screen. And since it is also your phone, you will always have it with you.

If you can wait ( I have heard of a Feb 2007 release date) you should consider this device.