Hi James..
I'm a pro underwater photog and use high end photo/video gear underwater..(Nikon D2x and Subal housings) If you have an interest in underwater photography I suggest getting the best housing you can for your $.. The thing to always remember is that the light goes through an extra peice of glass (lens ports)- Thats where the quality is so important. Also, You will find that you won't be satisfied with the quality of images from cheap housings...
I suggest, If you are starting out with underwater photography and have a limited budget to get a Nikonos V underwater film camera. It's all manual and it is the cheapest way to find out- 1, if you actually enjoy it (It's the hardest photography to do)and 2 - getting used to useing one underwater..
People think it would be easy, but in fact it's the complete opposite....lol
Hope this helps..

Dave