USB playback - opinions needed please

[skru_fase]

Hey guys, I have a stock BMW Nav system (in an E46), and would like to keep it if possible, but add the ability to play USB sticks or SD cards via purchasing some sort of 'adapter'. I see that the DICE mediabridge would work, but I was looking to find something a little cheaper as I don't really need a lot of the functionality that it provides (Bluetooth, Sirius).

All I really care about is having a good interface to navigate folders on the storage, hopefully working steering wheel controls, and obviously display of the media on my screen.

What are the best options out there?

Comments much appreciated....