Very cool! Other iPad-based attractions/museums I've seen use what seem to be much better padded/armored cases, though. Hope these can stand the abuse!
(And if $32 is too expensive for a given family size; three good options would be a) having fewer offspring, b) choosing cheaper field trips for bigger families, or c) only take some of the kids on trips, while raising the others in the basement like mushrooms. All good options.)