I just bought a Magellan Sportrak Map. It's main use is as a speedometer on my 2002 streetfighter project but I made sure I bought one with mapping capability. It has 2 megs of built in maps and 4 megs for download. Mount kits and power cables are available for it, it's water proof, back light and has a nice big speedometer...
I got it off new Ebay with software for $145.
