Ok, I'm looking to go to Australia next spring for 4 months as part of a study abroad program and I would like to do some underwater photography. I dont want to drop a fortune on a housing, so I thought about one of those PVC bags but they're only rated to 15 feet (4.6m). I own a Nikon D50 and would like to know if 15' is a good depth and if the PVC bag is a good (cheap) substitute. Though I have found some that are rated for 66' they're about $350...(no thanks I'd rather buy a new lens or flash). Any comments advice or other ideas? Also, ive also looked into renting...but again, not a cheap substitued, least not in what i found.