I knew I was going to be going on a tubing trip, and couldn't yet afford a waterproof camera, so I scanned the selection on Amazon.com and ordered one of the least expensive waterproof cases I could find: a "DicaPac WP410 (10.5x16.0cm) Small Zoom Alfa Waterproof Digital Camera Case with Optical Lens (Clear)." I got it for $17.95.
Not bad! The case is of a somewhat thick and unwieldy plastic. You slip your digital phone into it, then "waterproof" it in 3 steps: First, you squeeze shut the "ziplock" seal, then you fold the end over 3 times, and then you velcro what's left of the end shut, so it's less likely to come unrolled. There's a special extension on one side for the telescoping lens of a standard digital camera to extend, which can be unscrewed, and the lens at the end was very clear (though I suspect I may have trouble keeping it that clear, if I start splashing water on it, or accidentally touch it, or let it get dusty).
The pictures I took with the camera, while in the case, turned out amazingly good. BUT -- you MUST make sure each time you turn the camera on that the extending lens fits into the proper opening. When I handed the camera over to a friend to take a few pictures of me, she didn't recognize this, and so the lens seems to have caught in an awkward position and some of her pictures of me are blurry with a sort of hazy halo around them. Other concerns are that the velcro holding the rolled seal keeps coming undone. I doubt this will be a problem on a kayak, but I would be wary of trying this waterproof case underwater.
Still, compared to the cost of a waterproof camera, this DicaPac case turned out to be more than sufficient for my needs.
