Can someone recommend a waterproof case/housing for a Sony a37 for about $100 or less? I have a 18-55 lens. Sould be good to a depth of 30 feet. I have only been able to find waterproof bags but I would prefer a plastic case. I am in Maui and would like to try snuba or scuba diving. Would greatly appreciate any help. Should I use a cheap waterproof P&S instead?