You can go to
Dukes Car Stereo
Best Buy
ABC Warehouse
CraigsList/Amazon/Ebay if you are that dedicated
Any car specialty shop
If I wanted to I could order them from Hank Graff Chevrolet though their parts/accessories/audio catalog and I was also shocked to find out they were selling MTX subs.. just blew my mind because I never see anyone under 45 in the showroom i guess they like to bump and thump too.
All in all pretty much any store that deals with electronics and any kind of audio will have receivers of all kinds. I know the guitar center carries subs and amps but I'm not so sure if they carry receivers " I'm a drummer so I don't use amps for all of that so thats why im not sure if they carry receivers but it doesn't sound like they would. " just a little side information if you wanted to go into a detailed search for finding your favorite.
So you are looking for a receiver with RCA jacks for your ipod
now days most of your receivers" and all alike" will most likely have RCA jacks " not all, but a lot of them "I like to stick with JVC as they had always treated me nicely.
Kenwood Receivers are nice