BMW Repair: 2001 325i repairs, spare cars, 2001 bmw 325i

Question
My 2001 BMW 325i has 89,000. I bought it new with the idea of keeping it until it had 150,000  miles, but every time something goes wrong with it (which has been a lot lately) it costs $1000 or more to fix. I'm told the engine and transmission are "bullet-proof," but I've had to replace fuel injectors, transmission solenoids, multiple window motors, etc. At what point does it make sense to cut your losses and get another car? I realize it';s an individual decision and tolerance level, but any guidelines would be appreciated.

Answer
My personal guideline is when you no longer trust the car.  I've got a'92 325 with 160K, a '95 740 with 130K, and just sold my '85 635 with 110K (not because of lack of trust).  But I'll work on my own cars, so if something like the ones you call out go bad, I replace them and it's not a major issue. (also have "spare" cars around so am not stranded.)