Gamegear have these on sale:
Waterproof Pouch $29
100% Waterproof Pouch for carrying all your important bits and pieces.
Fold down the top, then clip it closed and thread your belt through the loop at the back.
Made from PVC Tarpaulin, with a light ripstop nylon lining.
Size of the Pouch is 22cm high x 14cm wide.
They all so have a much larger version Size is 34cm high x 28cm wide. made to be carried in the small of your back.