For good underwater quality pictures, to a certain extent, you get what you pay for. With that said, price isnt always everything. If you buy a $30 underwater camera, from a big box store, quality probably isnt going to be that great.
There are some relatively in expensive underwater cameras out there. There are also filters, like mentioned before that can be added to cameras, to help the pictures "pop".
Depending on what a person looks for in a camera, and how often and what they are going to use it for, I would suggest theses cameras:
The Olympus TG-320. Its a point and shoot camera, with digital zoom and waterproof up to 10 feet on its own. Olympus does make a housing for it, should you want to go deeper. It also has 720 video capabilities.
The Olympus TG-630. Basically the same as the 320, only has a better sensor, 1080 video and water proof to 15 feet on its own. It also has a waterproof housing for deeper depths.
Both the 320 and the 630 can be had for less then $200.
If you plan on diving, The Sealife DC 1400 camera is one of the simplest cameras out on the market. Its a little more expensive at just under 500, but is very user friendly. It has 2 underwater modes, which automatically correct the color based on your depth, and multiple land modes. The accesories by comparison, are less expensive then some of the other cameras out there today. Moving the camera setting from 1 mode to the next takes about 30 seconds at the most. To go from still pictures to movies takes about 1 second.