You can buy Bilstein replacement parts for about 70 bucks a side and have a suspension shop put them in and re-align. This is a very common issue. Total cost about 300 bucks. A lot less than $1,500!!!!

FIND A GOOD INDY. Do not go to the dealer for anything!!

Here's an Ebay example you can buy BMW E53 x5 3 0 4 4 4 6 4 8 Left Rear Upper Control Arm Subframe to Wheel Carrier | eBay