I just remembered this...
The first time we went to one of the waterparks we inquired about the waterproof holder for our money. The CM gave us the option to have a mini Disney Gift Card on a bracelet instead. We added money to it and kept it on our wrist with our locker key. We saved the $6.00 that we would have spent on the waterproof holder. It worked out great.
Plus, I let my husband use it for the rest of our trip- like it was his little allowance!!
I think he still has it. If you lose it they will replace it as long as you have the receipt.