I hacked a Vivicam 46 camera for a motion sensor camera project. I picked it up at walmart for $19. The only drawback is it doesnt have a flash. If you can solder, it's an easy hack. Here's a pic and some instructions to help.
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Open the camera and locate the power and shutter buttons. The board should look similar to the image above. You will be soldering wires to the solder points labeled A,B,C, and D. Unforunately, I dont remember which solder point controls which button but I do remember "A" and "B" were one button and "C" and "D" was the other button. To figure out which is which, with the batteries out of the camera, place a continuity meter on points "A" and "B" and press one of the buttons. Do the same for points "C" and "D".
I used a couple opto-isolators to trigger the buttons.
Hope this helped.