$200?? Try $2,000 or more for an underwater housing. There are plastic bag type cases that are in the couple hundreds, but they are meant for the surface.
Light and Motion LOL
The most cost effective camera case may very well be made by the camera manufacturer, and often found on ebay for a good deal.
Edit: Ikelite is the clear housing manufacturer. Check ebay for used, then go through it. If it is an expensive camera and you plan to submerge it, than insure it for flooding.
(Message edited by Peter_C on April 28, 2008)