I tried to order from them but received this a few days later:
06/22/11 11:8 AM - **UPDATE** Part #s 71600009711, (TRAILER HITCH KIT) are currently on national backorder from BMW. Typical backordered items arrive to our facility in 2 - 3 weeks from Germany. We'll process and ship your order once all parts are in stock (unless otherwise requested). No charges will be made to your card until the order is complete/shipping out. Please periodically check your order status for future updates. Thank you for your patience and support! -getBMWparts.com

Hopefully it will arrive soon.