Most owners feel that BMW's "lifetime" transmission fluid is a fallacy, so do change the fluid. $2K is ridiculous. Look for a shop offering the BG power flush & fluid exchange - we used a shop in Dulles VA & had this done on the '00 E46 with no problem at 60K miles. The BG fluid was compatible with the BMW/Texaco AT fluid recommended in our transmission.

https://www.bgprod.com/catalog/trans...change-system/