I know I'm a day or two late, but if you are still looking for a fairly cheap UW camera.... When I was living down there I used the Kodak 35mm disposable with a flash. I just bought them at the local shops in town. (and if you are careful you can open it up and reload the film so you can take 5-6 rolls without having to buy 5-6 disposable UW cameras). The pictures came out great if I had them developed at a professional film lab (here in Colorado it's Mike's Camera) or through a local dive shop, or if you are lucky...a one hour place that knows what they are doing as they will need to adjust the color. I had a few roles devolped there at Belicolor and they came out really nice.

Only downfall....you can't take them very deep. About 20 feet and then if you go deeper you have to come back up to advance the film. Works great for snorkeling trips though. smile Hope that helps and the grand-daughter has fun.