Transmission on 2005 BMW 545i

Our BMW is making a banging sound in the transmission when we excellerate. It can make the car shudder. With only 45,000 miles on the car, the idea of replacing the transmission rather unappealing. Any idea what the cost of replacing the transmission is? Also, the warranty expired, but is there a chance BMW will stand behind their product. I thank you for your time and consideration. Warm regards, Mark

Asked by for the 2005 BMW 545i
Before having the transmission replaced make sure the rear u-joints and center support for the driveshaft isn't making this noise and you can find a shop here