I won't hazard a guess on the amperage, but unless it's ridiculously high amperage you could convert a PC power supply to run it. You can get one that claims up to 60 amps at 12 volts for reasonably cheep, although unless it's high end I'd be surprised if it could reliably pull more than 30. Conversion is
resonably easy if you know how to solder, with the added bonus that you can teach your girls how to solder as well.