Hi Bugman, if that is what you want to do your best bet is a PDA or palm pilot running ozi explorer or similar. I run 4 different gps systems these days and the palmpilot with gps receiver is by far the best.
Cost wise it can vary because of the amounts of pda's to choose from and the gps receiver would cost under $150. Pda anywhere from $100-$600.
I also run a garmin 60 csx which has excellent capability but nothing compared to running the palm.
You can have sattelite pics on the parm, maps of everywhere, made up tracks to follow, google earth shots....
Xav