to put it into proper perspective, yes mas mahal ang parts at hindi sentimos lang ang difference. the other side of the coin is as long as you regularly observe regular maintenance intervals, the bimmer will last a life time.
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if you'll buy 2nd hand, make sure that the car is already in acceptably good condition. if you're thinking of an E36 320i, its weak points are the water pump, rack and pinion, rear subframe suspension parts, and the weak adhesive of the ceiling pad. so, make sure these parts are a-ok.

if you'll buy an E46, i heard that its water pump is also kinda weak. a quick trip to a dealer with a computerized engine scanning device will also help.

good luck in your search!