Cheap is all relitive. In 1992 I bought a cheap Cherokee 235 for 25k, 6k later I had a pretty good airplane. 4 years later, after a catastrophic engine failure. I got to put a new engine in it. Lost my a$$.... Also during that time I owned a flight school/flight club with all leased airplanes.
for a little background information, an FBO doing lease backs is looking for two types of aircraft. The first type is a good trainer. C-150/152, C-172, PA-28...... The operating costs are low, they can fly the P*** out of them without worrying about heavy maintanence. The second type FBO's are looking for are airplanes that people will rent for pleasure. C-182 (RG), PA-28R, sometimes a PA-32 or C-206. In rare cases someone will lease back a twin, but this is usually a money pit for the owner.
These are the most standard aircraft at FBO's. Some places will get into speciality stuff like Champs, C-120/140, short wing Pipers, and such. But insurance costs and min pilot requirements usually make these prohibitive.
Ok now that I have digressed significantly, I'll get into the advice catagory.
If you want an airplane that is inexpensive to operate and can be leased back, I'd suggest a 152, an older 172, or a Cherokee 140. Stay away from the odd ball stuff. Piper Tomahawks, Colts, Tri-Pacers, C-175's, and Tri-Champs all fall into the odd ball catagory.
If you want an airplane which you will keep for a long time and own it because you really like it, then all bets are off. Buy what twists your tail.
I hope this helps you figure out what you are looking for. I also suggest buying a current copy of Trade-A-Plane or Aero-Trader to get an idea of price ranges.
Oh yeah, the cheapest to operate and easiest to maintain airplane I've had contact with, is the old Ercoupe. They can be bought for less than 15K, burn 4 gallons of mogas an hour, and are really fun to buzz around in. I think there is a wing spar AD, but if that has been complied with, you are pretty much home free.
good luck