Not sure where the U.S Dollar vs Australian Dollar is today (or how much the electronics cost for you, been to Australia, have lots of friends there, love it alot, but I thought some things were more pricey like computers, but it has been a few years so apologizes ahead of time due to rounding or price differentials.)
First, I have shot the 3040 and 8080 Olympus alot and love them, but have not played with the 7070 (though I heard great things about it.) The 7070, like the 8080, is disconitnued but you may still be able to pick it up used. You may want to take a look at the C7000, has good specs (though slow on cycle times for RAW and may not shoot long movies) but it is available for under $400 US (have seen it for $320 US0 at amazon.com via B & H) and the Ikeleite housing is $264 . The big drawback is that the housing will not let you attach a WA and you will have to shoot manual strobe (no TTL, which may or may not be a concern.) If so you can look at the Sea Spy which has a lens ring that (if I recall correctly when I checked it out) can use a WA Lens. (Not as many controls, but they can customize it and havee made them to work with C-7000) You can get the DS-50 strobe with a controller and basic arms for about $515 there, so for $1000 - $1200 (add $250 or so more for WA) US you have something that may work for you, strobe, camera, WA. (Also as an aside I prefer my Sea & Sea strobes [at least so far] to my Ikelite strobes.
On the other hand, something to consider (if you do not have to absolutely have to have movies or are concerned about shutter lag and RAW cycles) is one of the Fantasea Housings for the D50, D70(s) or Canon Digital Rebel, they are $899 US. (The Ike housings are about $300 more and slightly bigger) I have seen REAL LOW prices on some sites for these (though I gotta question whether they are legit) and decent prices such D50 with lens for $535, from places I have bought from before.), so for about $1400 US you have an SLR and housing (I am going to get one of these combos shortly, once I convince myself to make the stuff I have to carry slightly bigger once again
) and can throw a smaller strobe (less $$$) in the mix.