I bought a sony 10 disc changer off of ebay for $100, I have a sony head unit so it matched right up. It's nice, probably 8 of the 10 cd's in the changer have never left since I bought it last march (and that was with a summer driving four hours nearly every weekend). It's in the center console of my truck, so I can change CDs very easily, although I did debate getting another cartridge for it so I could swap in another 10 CDs while driving, but I decided I didn't have enough music to make it worthwhile.
I looked at getting an ipod, but I figured the $100 investment was a better deal for me, because I'd only use the ipod in the car. Plus I don't have to worry about taking it out of the truck every time I park it.