Hi jrsxtn
A couple of extra thoughts and to add to what others have said. Much depends on what you are trying to achieve and how choosy you are. For some the sort of snap pics that you would show your friends may be good enough. But if, like many of us on the forum, you become a near-obsessive, perfection-hunting nutcase, the sky is the limit.
The suggestion of the EM-5 is a good. I know people too who have made careers out of using the Canon G series with an Ikelite housing. I think they may cost less than the EM-5.
As Xarifa explains, you can always upgrade. Bear in mind that if you make the right choices over a few items - especially strobes and arms, they can grow with you and you don't need to change them. Chances are the camera and the housing with be something you might change every few years. Have a look at the Inon strobes (especially the Z240 - almost an industry standard) and ULCS arms. You buy the arms once - you need never buy again.
Just to help on the "bubble port" issue, a "domeport" is what you usually need for wide-angle photography using a wide-angle lens. Shooting macro only requires a "flat port" but because of the nature of wide-angle lenses and the way they deal with the underwater environment, you need a curved port to photograph wide-angle. These are usually more expensive than flat ports but are, if you want to shoot wide-angle, key.
Hope this adds a bit more for you.