For the cost of a new stock radio, I think they are $200... I don't remember if that was the price for a refurbished one or a new one... and it was from one shop here in San Diego... AND it was my dad who talked to the guy, so don't hold me to that number.
I kept my original radio with the cassette (makes it easy to plug my ipod into it, too) and got a CD changer for the trunk (I posted the info about it on here years ago). Are you sure you wouldn't want to do that? I like it because I know that no one is going to break into my car to steal my CD player.