I'm actually using CHDK and the cannon cameras for my current prototype, and have even written custom software for my desired functionality in ubasic.
I'm striving to slash the cost down to smaller and specialized component units.
Needless to say, I would have to account for manufacturing and assembly efforts.
I just can't believe that using retail cameras are the only cost effective options
(maybe, I should change gear and see what can be done to make such products available