Several years ago I bought a cd-based caller from a company that has been in the game call business for years. It was overpriced and the speaker was useless.
I put a E-caller together similar to the link below and it sounds good. The only thing I've called is crows, but it sure brings them in.
An MP3 player with enough memory to hold a bunch of sounds is the way to go. Plenty of free calls are on the net and you don't have to worry bout changing tapes or cds in the woods.
http://www.predatormastersforums.com...eecaller.shtml