iPod Cable needed to control ipod through car stereo

Hi, I just bought a new Hyundai Elantra. It has a USB port, and I can play my ipod Nano, but am not able to control what it plays through the stereo. Even if I set my ipod to play a certain playlist, once I plug it in it just starts playing random songs or podcasts. The dealership has offered to sell me a dual cable, but I find it very expensive, and so I've been trying to find an alternative at electronics store sites, with no luck. Does anyone know where I could find such a cable? Thanks!

Thanks!

I'll try one of these