OK, I forgot to specify something
A cassette player wouldn't really work, because the idea is to have the project stand on its own...a cassette deck would need to be rewound, or have the tape flipped, plus if someone pressed stop in the middle, the next person to press play wouldn't get the full experience, they'd just pick up from wherever the previous person left off...
What she needs is something that could be triggered, and simply stop when it's done playing, ready to play again.
Radioshack used to have a little digital playback kit you could build yourself that would do pretty much exactly what I'm talking about...except I can't find it anymore.
MPEDrummer