Does anyone know of any affordable locking cases/boxes for iPads? I have 4 iPad minis in my classroom and am looking for a secure storage solution since my middle schoolers have sticky fingers. Many of the ones I've found online are several hundred dollars. I'm looking to spend less than $100 (preferably much less since I'm a teacher). It doesn't have to be iPad specific, but it needs to lock. Anyone have any suggestions or good ideas? Links would be great. Thanks!