For out of warranty work I personally would take it to a Indy shop that specializes in BMW's since the dealer charges a exorbitant amount of money to fix your car. Also something this major I would call around to see what other shops are charging to do similar work or actually take it to them for a second opinion. Just my 2 cents.
2009 AW 535i
-Sport, Premium Package, and Comfort Access
-FBO, custom Cobb E45 map, Performance Gearing LSD.