Chris.You can buy a fair amount of gas for $500. A good map and compass don't lie.
--I always take both... as Chris already has most of the paper copies the Garmin with Same Backroads maps as back up.
--I found now that Forestry does not enforce nor insist on road maintenance... even when it is required... not talking about roads that are not supposed to be maintained.
--I found in 100 mile area some FSR... that were so poor I could not believe I had found the correct junction with my maps... The GPS confirmed that
--I was at the correct junction thus I tried the indicated road... of course after going down a better maintained road about 30 meters away that seemed to be the correct road. What I found especially if driving with no navigator that the GPS unit allowed quick reference... this was of particular importance when hunting as some of the roads are boundaries of hunting units with different regulations. The GPS was reassurance that I was in the correct unit etc.
--I always carry back up map and if possible air photo or downloaded google map of specific areas of interest.
--Other use was for finding closest highway access or Gas Station.. again the GPS gave time and distance references that proved to be useful.
--For use in vehicle get largest screen you can afford.. if you intend to carry in the bush as well then a compromise with addition of a water proof case.
--I don't know how the interface works but I have seen some with hook up to their lap top as well giving a much larger area map.
--If you take a look on the Backboards map site they give some suggestions for compatible units.