there is the fm transmitter thing they sell at walmart for 30 bucks.U plug it into ur cigarette lighter plug and turn the radio to 88.1 or whatever channel u set it to and it works perfect. i was using this thing for quite some time but than it was time to upgrade.
i hope that help
1997 E36 M3
1991 318ci-Project Car-Almost Done
93 Honda HB-Daily Beater