If you are only going to 30' you may be able to get away with heavy duty sealed bag
They actually make them for cameras
http://www.scuba.com/shop/product.asp?category=49&fromsearch=1&hashvalue=030615
They advertise for a depth of 60'
Pressure will be a factor, if it compresses the bag too much it could press against any part of the camera & cause a leak
Sharp "pokey" stuff underwater is anothe rproblem
If you want to DIY, I have seen cyclinders created, sealed at one end, clamp shut at the other. Most of these have been for video - put it in, turn it on, seal the door, dive - it stays running
For a camera you want to be able to use the functions
For film a remote shutter button was used, not sure if yours has that capability
When I was looking for a Digital camera, everyone I looked at, I checked 1st to see if I could buy a housing
This is the one I bought - made for underwater:
http://www.scuba.com/shop/display.asp?id=068626