Thanks to this thread, I was motivated to rig up my 2008 C350 with Blutooth Audio through the AUX port. I stumbled across the Aluratek iStream Bluetooth receiver at Best Buy ($29). It is small, convenient and easily paired with my iPhone. I then ordered the Sound Shocker Pro. It was quickly shipped, and once received, it took me all of 4 minutes to plug them up and pair, and to be listeninhg to the Bluetooth Audio being streamed from my iPhone Through the AUX channel. I had a spare 12V charger "plug" with USB ports in a drawer, so that is what the Aluratek is plugged into for power. It was so easy, and it works great.
Here is the link for the Aluratek iStream: iStream Universal Bluetooth Audio Receiver | Aluratek
The url for the Sound Shocker Pro is listed above previously.