I have a original OEM BMW 2G iphone cradle for the 6NF smartphone option. This cradle allows you to listen to music on your iphone, charge the phone and use the external sharkfin antenna for improved reception.
Part number is 84 10 9 164 213
Cost is $90. Free shipping in the USA.
A bargain as they retail for $175
Shoot me a IM if you are interested.
Note: iPhone not included in sale ;-)