The other, bad, option is to get one of those greeting cards (or stuffed animals or books) that records a message from grandma to the kids. Press a hidden button, it records for 20 seconds. Press the main button, it plays back.
The only easy signal input is via a 3-cent microphone. (Output may be another hassle.) There's about 2 cents of digital storage. The fidelity is awful. They are not meant to playback looping (though jamming the Play button *may* work). And funny enough, they are awful hard to find at the right price WHEN you need one. Several places sell cards books bears for $30-$90 every day. Once in a while they go to surplus, but never when you need it.
Ian's cheap MP3 is probably a FAR better place to start. Unless you happen to have a recording-bear sitting unloved in the closet.