i was hunting the same thing.
Look at this article from another forum:
I have: Alpine, Model CD53, Part Number 65. 12-6 961 214 (Dec 2005-May 2006) iPod Data, Aux, Sirius and MP3 Capable (not sure if it does Sirius though...)
If you find that too expensive, i have just a normal CD player for BMW that i can sell to you for $100.
Let a brother know.
***PS: as far as i know they are all the units are plug-and-play.