I use a Garmin GPSMAP 60CS (no longer in production). Pretty accurate with the quad-helix and can attach to the mt bike or clip to a backpack when hiking. Sub-300 bucks. Obviously, it will not tell you when to turn when offroad, but will backtrack. It will direct you while on paved roads. The CSx (replaced CS) model runs a little more $$$ and has a better processor and Micro SDram slot for more maps if you desire.
http://www.garmin.com/products/gpsmap60csx