I've been looking into a relatively inexpensive U/W digital camera setup. In so doing I've been lucky to consult with someone with a great deal of experience and expertise. Anywho - after much lookage the name Casio came up. Turns out the Casio Ex z50 uses pentax lenses, is very quick and quite good in low light. Casio makes a dynamite little housing for it as well - which is good down to 40meters. I've found the camera for $299us and the housing for $200. Casio also makes housings for their very small lower end cameras - looks like even with the housing they'd fit into a smallish pocket though the best they do is 2 or 3 megapixels.
Anyway - I thought I'd share what I've found so far.
Anyway - I thought I'd share what I've found so far.