I really dont know the best place for repairs ,but in the mean time , This is what I would do,,,,NOW
Get a video camera set it up next to the P3( for referance) Take apart the shell, Have some little zip loc bags , group and mark every nut bolt in the bag.
Air in a can in short burst then Put a fan on it, or ,put it in bags of rice(treat it gently while in the rice), for a few days.
I would also (if possible ) take the lens and the back of the camera off.(I would think that would be the most expensive part.
Salt water is a whole different animal. Even if it gets up and running ,unless you give it a bath in fresh water it will eventually corrode