Urban Outfitters SuperHeadz Plamodel DIY 35mm Camera ($28) would be a great way to see just how a camera works. Much like a model car kit, the camera comes in parts that you separate and then snap together, but unlike the scaled-down versions of cars, this kit produces a working camera--albeit without a flash. The kit includes a vinyl bag, wrist strap and screw driver. No batteries are required for opperation and it takes good old 35mm film.
Picture taken with the camera: