Why would my transmission go out with only 72,000 miles on a 2007, 530i?

Thanks Tom, just picked it up from that mechanic. Paid him $125 for his estimate and took it to another BMW certified shop. His breakdown of charges: Transmission $4588.39, Engine oil pan $713. 90, bushings $588.37, Oil filter $643.36, water pump $922.40 and struts $1047.18....said this was all normal wear and tear maintenance. Does that sound about right that these things would all need to be done now because of the transmission....

I agree. Most repair shops are happy to charge retail for any and all parts. They make good money on the mark-up. Some repair shops will let you bring them the parts. They just will not warranty the parts, only their labor. It will not work that way with the transmission. Also, with that few miles on the car I wonder why the shop is recommending all these repairs. If it was driving OK until the transmission problem arose, stick with the draining of the swamp and then decide if the car is worth the extra money and effort. My personal thought is the BMW transmission and engine starting about, I think, 2004, (Not the hardware itself) but the maintenance design controls is to help the hardware destroy itself with no easy access to the oil levels or be able to see the condition of the oils. Regardless of what BMW says nothing is life time unless it is the designed end of the life that BMW wants your car to self destruct. They all require maintenance, GM, Ford, Chrysler, Etc. all recommend certain intervals So do the BMW's. The other thing you might consider getting a used transmission and installing that.