1985 BMW 325 in Michigan (USA)how much is it worth?

I'm looking at a 1985 BMW 325e that has sat out in a parking lot for
the last 6 months. The owner says that the rear end has gone out on it.
It has 165,000 miles on the original motor. It has a standard
transmition, and no air conditioner. The body is fair, but a couple of
small rust spots are starting on the rockers. The leather seats are
o.k. accept for the drivers seat which is pretty much worn out.

Are parts easy to find? Anyone from the Michigan area know where to get
salvage parts?

How hard is it to change the rear end out?

What other things should I look out for before buying this car?
Thanks,

Steve