I think your dealer is full of it. From what I understand, you already have all the components needed for Bluetooth except for the programing and plugging in the wires. If you go to your dealer they should have the aftermarket catalogue and it runs for about 500 dollars. I have an 06 E90 325i as well and from what they told me is that you only have to buy the package after and they will install it just like it was Syrius radio. Somebody please let me know if I am wrong or there is more to this.
Frank