OP, if you're looking for a great place to get a cheap, used Android, Swappa is a nice site:
Swappa (Android) Buy and sell gently used Android devices
As others have said, a used Android with no cell connection (assuming you have wifi available), is a great option. If you can stretch your budget a little bit, they may like a Nexus 7 (which they can certainly share with you as it offers different user profiles).