That sounds like a decent bus to me, and a not unreasonable price. You might be able to get them down a bit with some haggling.
I'm partial to Thomas busses (I've owned 2 rear engine ones). I personally like the 5.9L Cummins. Cruise control, and 75mph and 100 gallon tank and 6th gear transmission? yes please. You mention air ride suspension, so I'll guess it also has air brakes?
If it fits your budget, meets the needs you're looking to work from, and is low rust and mechanically sound, then it sounds like a good deal for you.
Is it a flat nose or a dog nose?