Um... Tips I have picked up here.
1. Pictures are great. Lets you remember what you saw, and allows others to point out things.
2. Listen to what the Sales Weenie says when you ask him questions, and I do mean LISTEN. There is Always something that they dont say. You have to catch them trying to avoid it...
3. Look for Rust, bad paint, and general Crud/Crap. If it looks like there is too much Rust or Crud, might consider walking. Bubbled paint indicates rust, single bubble is a rivet.
4. If they have the bus running when you show up... You need a new battery, and maybe have a short. I have heard two stories where this has happened, maybe three, cant remember.
5. Test Drive it on City Streets AND the Freeway. Anything less than 20miles and you cant be sure that the bus is all that they claim. No Test Drive, not a good idea.
6. Auction Sites are NOT for trusting people. Too many times have people bought vehicles that "Run Great" or are "In Great Shape" and arn't.
I am sure there are others, but I am too tired at the moment to remember them. So I will invite others to fill out the list.