looks like quite a beater for that money. I would definately offer less.
I bought my 86.5 N/A for 2k and it looks like this
Granted its not a Turbo, but it was prefectly straight and runs great.
I think you could get him down some, act disinterested or disappointed about all the body and paint work. Give it a complete looking over mechanically and if you know someone who knows cars at least somewhat have them go with you. they might see stuff you dont, and a second brain to bounce it off is always good when deciding if its worth it or not.
Good luck though, and welcome to the community if you decide to go that route