Buying a used TT that's been sitting?

I would check and make sure it has pink stuff (antifreeze) in the water lines. New tires for sure. Walk on the roof and look for soft spots (carefully). Look around inside for ANY sigs of water leaks/soft floors/stains. Get it plugged in and check if all appliances work correctly, especially fridge and a/c

Plan on a short delivery trip and servicing all axles and brakes fully.

As far as price, I don't know much about that model...