I know I am behind the curve here, but I am a fairly active unwatered photographer.
Like with anything else in photography, what are you wanting to shoot, how are you wanting it to turn out, how much are you willing to spend and last but not least how much effort do you want it to be.
A P&S camera in a basic housing will be relatively inexpensive, quick and easy to use, minimal weight, but is limited in the kind of images it can capture. Even the GoPro is a popular option and it can do some nice things.
Going to a DSLR gets expensive fast. I see you linked a housing, but that does not include the port also needed, strobe(s), strobe arms, cables to fire strobe(s), focus light. Then you have many seals that need to be properly maintained, because a leak likely means damaging your camera and lens which equals $$$. They are large and heavy to travel with, mine is 22.5 lbs.
With that said, I love my DSLR underwater. Our last dive trip our luggage did not make it to us until the 4th night. I had my camera with me and had packed all my batteries in my carry on. I am able to get by on rental dive gear (not preferred), but I can not rent a DSLR in most places.
When I first started diving I thought I was going to get a UW housing for my Nikon D90, then like you I priced things and found out I was not

What I ended up doing was finding a used D70 in a UW housing with strobes and a 10.5 mm fisheye for a great deal. I shot it for almost 2 years. Then I found a deal on better strobes, so I added those and sold the old ones. About a year later I found a used D90 housing and sold the old housing. I am still using the same port after about 6 years now.
I shoot mostly with a 60 mm macro but also still have the 10.5 mm fisheye and use it some.
Here is a link to my albums, feel free to look around. I have lots of diving stuff on there.
John Nokes