Seriously, the junk yard.
You may need to call ahead to see if the one near you gets BMWs because (in
my area at least) the yards tend to specialize -- Domestic Big Three,
Japanese, European, etc.
When a car is totalled by the insurance company, it goes to an auction. The
bidders (junk yards, generally) bid by country of origin. The yards that
take BMWs would speicalize in them. They may take Audis and Vovlos too, but
would tend to not take Hondas and Toyotas or Fords and Chevys.
This is not a hard and fast rule but it deserves consideration, and a phone
call to see where the yard is that has the parts you want.
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