1. Wal-Mart is evil. 2. What you're going to need is an FM transmitter that plugs into your iPod's headphone jack then plays music through the radio. They come as cheap as $30, but this is a case of "you get what you pay for." Buy a nice one to be sure of getting a good signal, especially if you live in an area with very little (rural) or too much (city) radio activity.
If you have a tape deck, definitely go for a tape adaptor, which is cheaper and simpler than a radio adaptor. It's easy to find; it's basically just a tape with a chord to plug into the earphone jack of the iPod.
made a walmart run. got one that plugs into the cigarette lighter (i'm getting a cd player put in this week, but in the meantime, roadtrip coming up, need tunes) and this way i can still use it after i get the cd player.