The thing to remember is that on a car that old the mileage doesn't even matter, so don't get too caught up on the fact that its such low miles for its age. All rubber and plastic items - hoses, belts, gaskets, cold air intakes etc wear out and deteriorate over time even if the car isn't being used, so those items are still 31 years old and will be prone to failure. The good news is that many of those items are easy DIY repairs if you're handy with a wrench.
When you're talking about a car this old and this cheap, what matters most is its condition. Does it run strong & smooth? Are the tires, brakes & suspension in good & safe condition? Do the accessories work properly? Does the interior smell like a moldy gym sock?
Pretty much any car that runs decent and gets you from A to B is worth $2000 these days, so if you like it try to negotiate them down as much as possible and go ahead.
The only thing I would do is take it in for an inspection - a mechanic can check things like the ball joints & brakes pretty quick and tell you if its in good shape or needs $2,000 worth of suspension work.