Picked one up from Autozone for my 4.4 a month ago, for about $110-120 out the door. I got a ride to Autozone from work, where it died, picked up the battery, and then swapped it out in the parking garage in 20 minutes using the BMW tool kit. Works great and starts much stronger then the OE BMW battery that I replaced. Just go to the Autozone website and you can search to see prices as well as what local stores have the battery in stock.