I have a Sony Xplod head unit I installed in my car. It works for calling which is very convenient, but the real money comes from the Stereo Bluetooth. Start the car, it connects, I fire up windows media player and im rocking out to the music on my 8gb TF card. Most def worth the investment. I picked my head untit up for $140 on sale.
Here is the one I have.
http://www.xplodsony.com/article/MEX...ed+CD+Receiver