I run GPS. the best features you want are self mapping on the screen and being able to save it. another thing i like is that i can hook it up to my pc and print out maps for other guy that want them. now you can get a good unit that can do that cheep if you look on e-bay. like the garmin gps3 unit. a friend of mine bought Etrex for about $300 i am sure you can find a good used one. but that is what i wish i had just because it holds the maps in memory
I've got a Garmin Emap, its great for woods riding because you can buy a handlebar mount and a garmin "helmet", a rubber covering. Good map and backlit for night by pushing a button. You can save data and upload data right from your PC. Its also very light and small. I think they retail for around 250.00. Check out www.Garmin.com.
I've got the E-Map too and it's a great mapping GPS. I've seen them discounted to about $200.
The hot ticket is the new Garmin Rino, which incorporates a GMRS 5 mile FRS two way, with mapping and a "buddy locator" feature which identifies the location of other Rino users on a mapped display. Very cool unit.