Since i bought one used about 5 yrs ago I can give you thoughts-be careful of the following:
-as stated previously the timing chains and tensioners will need to be done at 100K miles. $800-900 .
-i understand virtually every one of these engines had bad head gaskets that will inevitably start leaking one side or the other. While the gasket alone isnt that bad u will find yourself in the mode of "while I got the heads off i might as well"- valve job, seals, etc. So be ready for that -$1600-2000 or so is cheap.
-the engine management system on these cars is the most complex design u can imagine. When they run they run but when they dont it is getting to the point where any honest independent mechanic will have real trouble figuring things out.
-shocks probably needed.
-normal rubber, wheels etc. take a look.

I must admit I have a love hate relationship with mine - at high speed i concur that the car is darling . The constant maintenance and the overly complex german design frustrates me to no end however. And the 86's were just the start. If you wait a bit you will be able to buy 500S's cheap that no one can maintain.