Cabelas is selling refurbished Garmin Oregon 450T units for 250 bucks right now. They come with the same warranty as a new unit. I got one and they are quite user friendly for a novice to GPS. (Me)
Definitely invest in the extra chip for the states you want to hunt. It's money we'll spent.
BTW........ Topgun 30/06 is quite right about WY region Y. The south end of Y is the best for muleys and your GPS will come in handy because the area is a patchwork quilt of mixed up public and private land and its vital to know right where you are.