Water filming

any of the waterproof cameras

GoPro and knockoffs

Nitroplanes.com has a decent knockoff with a good set of mounts. Very close to looking like a GoPro. GoPro fits the waterproof case but the buttons don't line up.
No idea what is easily available there...

Look at the Nitroplanes.com camera. Its roughly 1/10 the cost of a real GoPro
Does not have the bluetooth like a GoPro, but that shouldn't be much of an issue.

Find something locally that is similar.