Check both the KBB & NADA for car valve minus the BMW parts + service.
1) A DIY Air cond service canbe bought at Big Lots for $8.00 (134a)can, also buy two new schrader valves for the Low/high pressure side of AC.
BMW Air cond service could be anywhere fron $150-$1500!
Do you really need a Air Bag?
Don't forget the price of Catalytic converters, if one was togo bad.