[B767capt]

The reason it's so expensive at the dealer is because they have to reprogram or rather reset the adaptive battery charging system when a new battery is installed. I just went through this with mine. Dealer quoted 500.00. After reading different forums, the reset is required so the new battery isn't either under charged or over charged based off the old battery data. I bought a new Interstate MTP-93 battery for 129.00 and installed it myself. I have an 08 535i. I also bought the Bavarian Technic program and did the battery adaption myself. My daughter has an 08 328i so this applies to her car too. Worth the investment. Clears codes and can read them too.