It would have been tricky to use fake stamps, though perhaps not useful if you want an actual attendance count :)
LOL- well we had stamps made with our picture on them- totally legit, but I guess if one has never seen that before it might be confusing!
That sounds fun. Were they terribly expensive or difficult to get?
Nah, USPS.com. It directs you to another site. Standard postage plus a bit for the formatting and processing.