MB bumpers are expensive - your quote seems very reasonable if its a genuine replacement part. Last I checked the genuine replacement part for my W124 was in the category of 500 bones. So I promptly swiped one from the yard.

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2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)