First of all, welcome to HybridZ.org....I hope you find it a useful and informing forum.
Pretty hard to answer your question given the scant information provided in your post....a lot of variables go into your decision. Being that you're in AZ, I would accept nothing less than a straight, rust-free shell.
To get an idea of going market prices, have you perused our Classified section? I'm sure you'll be able to see several examples similar to the car you're considering, which should give you a decent idea of what it's worth.
Hope this helps...good luck with your search and happy motoring.