Recovering running trucks is MUCH cheaper than non-runners!
Personally, if I were you, I would go preview the trucks that you are looking at before buying them. Pictures look ok....but when you see it in person, it can be completely different.
Keep in mind that a new set of tires will cost you AT LEAST $1000-$1500....so it would make a lot more sense to pay $300-$500 more up front & save a lot more later. Other expensive things are: glass, soft tops, leaking hubs, bad radiators, headlights, signals, etc, etc, etc.
If you are buying & not previewing....then bid assuming that all that stuff needs to be fixed.
As far as mileage goes......10-11mpg w/out a cargo cover on, 8mpg with one on.
Good Luck!