[Padgett]

In my experience Craigslist and RVTrader are good places to start. You can find many posts on what to look for but the biggies as:
1) any sign of leaks in or outside particularly at the dump valves behind the driver's side (US) wheel.
2) is it easy (not one hand but close) to open and close
3) do all of the appliances work in all modes
4) are the seals/flaps in good shape
5) do the torsion bars have lots of adjustment left
6) are the tires/wheels recent and proper load range for the coach.
7) Does the door fit properly
8) Do the module latches line up properly when closed.
9) Is there a spare tire
10) general check for fit, finish, and signs of corrosion.

Some of the best deals are from a dealer who took one in trade but does not normally handle or know TMs. Expect "as is/where is" and should be priced accordingly (NADA Low Retail is a good place to start). If you want a really nice one find either a fanatical owner who is moving up/down or a TM dealer but expect to pay accordingly.

Just remember, "condition is everything".

ps a dealer may not allow you to take off the lot unless you have the proper equipment for towing including a functional brake controller

pps mine has a 2" ball hitch and a 7 pin (round) trailer connector