...or, spend a little extra when you buy your e36 for one that is BMW Certified, or a vehicle with a warranty. I purchased my '92 BMW from a great luxury used vehicle dealership down on Finch, the car came with a 1 year bumper to bumper warranty, and 3 year drivetrain. Sure I paid a little more, and taxes too... but I do think I made that money back in maintenance, plus there's nothing like buying a professionally detailed vehicle.
They fixed every little problem on the car that came up under warranty, including rear trailing arm bushings, windshield washer pump, window switch died, even replaced my foglight when it was stolen, and replaced one of my Type-45 BMW rims when it was found to be bent... they paid to have the tire remounted and balanced too. Most of the work they commissioned out to Munich Motors (the same place Tom got his e46 M3 swap done.), and after that I got my work done by Bimmersport.
Within those three years, my drive-axle broke. I had to pay for a tow, parts, and labour to get it fixed. I later remembered I still had a drivetrain warranty... I brought all the receipts to them, and they reimbursed me in full the next day.
One way or another, you're going to pay when buying a used (early-middle model) e36... buy private and buy cheap, but you'll have to do all this maintenance right away out of your pocket... or buy from a known dealership, and pay quite a bit more up-front, but at least have worry free driving for the next year or two. (would've been nice to know that your $7000 in repairs would've been covered under the bumper to bumper warranty.)