How much spending money to bring to Virginia Beach?

I am a scout leader bring a group of kids to Virginia Beach for a week. One of my parents asked me how much spending money there child should bring. All of their activity costs and food cost is covered, this would just be for the souviners. We will be spending three days at Busch Gardens and Water Country, a day at Jamestown and the rest of the time at the beach. Please remeber these are just kids and have already paid a good amount of money for everything else.