I prefer gassers, because my home town mechanic can do about anything that needs to be done to it. After all, it is just a (in my case) a Ford truck, and any good farm equipment mechanic can work on it. Any my local shop even has a 14' door and bay that he can get it inside with no trouble.
Under 50K is probably going to be a bit difficult, except for the lower-end units. look for under 5 years, and 30-40K miles. Your area is a good place to look around. Allegro is up in Red Bay, and most of their units are well-rated.