There is another option.
If your rig has an FM radio, you can buy yourself a portable Mp3 CD player (or whatever) and get one of these devices.
http://catalog.belkin.com/IWCatProdu...duct_Id=156016
They plug into your portable Mp3 CD player and you can then play the CD through the FM radio. I think from memory that they are about $50.
That was you have portable and in car sound.