[Efthreeoh]

OP, I currently have in the fleet 4 BMWs, three are over 100,000 miles, the forth is my '08 Z4 Coupe which is at 99,598 as of last night. I had a fifth BMW, an '89 E30 owned since new and sold 18 years later at 257,000. So I can say that I know quite a bit about owning old, high mileage BMWs.

Don't listen to most of these fools who are scared to own a BMW past the warranty period. 100,000 miles on a BMW is nothing; my E90 is over 300,000. Take your time to find the right car. If you want something still in good cosmetic shape, then an E46 or E90 in the 3-series variant with over 100,000 miles should be near $4,000 price target. I suggest keeping to a normally aspirated engine and a manual transmission for the lowest risk of funding a recovery process to get the car back up to snuff. Try to find one from a private owner where you can get most of the history on the car. Buying from Joe's Used Car lot, is a bit more risky.

The best thing about owning an older BMW is BMW keeps parts available for 20+ years for most models. The BMW TIS is now on line for free. The TIS (newtis.info) is the repair procedures for every BMW back to the 1970s. And the other part of the BMW TIS is the parts lookup system, which is realOEM.com. If you are a retired airplane mechanic, then repairing a BMW is right up your alley.

BTW, I just acquired a 2005 E46 330Ci Convertible for $3,000. It had 99,098 miles on it. It needed some TLC and some PDR is in the works for it, but other than that, it's almost in new shape.

Good luck with the search.