Krusty:
What can i expect to pay for a housing?
A lot
B&H has a few different housings for that camera, and they range from around $1100 to somewhat over $2200, if I rember correctly. Domes are usually extra, although I think the most expensive one has at least one port with it.
I've personally been shooting an old Nikonos V with an Ikelite strobe for a while now, and I really like its light weight and small profile. I got my girlfriend a Canon S60 with the Canon housing (5.0 MP), borrowed it a couple of times, just for "snapshots," and I'm now a digital convert. It's just so easy. My dives are generally long, since I use a rebreather, and one roll of film just wasn't cutting it when I wanted to take photos.
Last January, I was out diving in Socorro Islands and those of us with higher resolution point-and-shoot cameras got almost as good a set of photographs as those with really expensive housed cameras...at least, that was the feeling I got, having downloaded the complete set from some other photographers and combined them with my own.
The biggest difference I could find when comparing the two side by side was shutter lag - while my shots were the same, framing to compensate for shutter lag, or shooting lots of photos in sequence was difficult. It was also a lot more cumbersome to adjust camera settings (depth of field, shutter speed, etc.)
The housing definitely is better for handling strobes, too - a necessity back home in the murky Puget Sound. On the other hand, for less than $450, I can't complain. Attached are a couple of shots from the Socorros, using the Canon S60 in Canon's housing, and resized down to 1280x1024.
