Do you wish to retain the business radio? or do you want to change the head unit?
If you wish to retain the business radio; go on eBay and find yourself a FM modulator with a USB port that you like... plug in the modulatoir into ur cigarette lighter socket, program the biz radio to a designated FM(stereo) frequency; stick in your flashdrive into the modulator and you are good to go ;-)
change head unit?... well there's tons to choose from out there for your desired application