I'm at 200K km (120K miles), I had excellent compression at 180K when I bought the car a year an a half ago. I have replaced the timing and cooling systems, checked for oil pan bolts, and changed the oil every 5,000 km. As a result I fully expect to have the engine outlast our use of the car.
I bought an E30 based on its reputation as being very well built with long lasting engines (plus looks, handling, and fuel economy). The work I have done on the car has been preventaive, and possibly not necessary.
Having just refreshed the suspension, all I have left is a sloppy shifter, and seat upgrades. There are some external imperfections that can be chased over time. The car was bought as a daily driver for my kids, and as a car on which to do a rolling restoration. I am 85% of the way there - will finish up with around $12K in the car and never see that money back - but have a great (3rd) car that I enjoy driving. I doubt I will sell it but will probably give it to one of the kids in a couple of years.
$ so far
Purchase $6,000
2nd set wheels & tires $800
Cooling system $400
Suspension (Complete front & rear) say $1,600
Timing gear $750
Stereo $550
I figure about $2K to finish the interior upgrade and paint it myself.