There is a lot more climbing than just Araps and Buffalo in Australia. The Grampians (just near Araps) and the Blue Mountains (2hrs west of Sydney) are probably the other two best known climbing locations in Australia. There are lots of other places that you could climb at and really enjoy too, but the Bluies, Gramps and Araps are probably the 3 most popular "destination" areas in Australia.
If you don't have a rope or gear, it can be a bit tricky. Araps is probably the easiest place in the country to rock up and meet people, but at the very least you should have your own shoes, harness and belay device. You don't mention if you two do much climbing currently? Do you sport climb (clip bolts) or trad climb (place your own protection) currently?
If you like bouldering, then you should get a pair of shoes and a pad and head to the Grampians, there are thousands of quality problems at all grades there, and you get to enjoy some very nice scenery too.
Also, don't get your hopes up on "magnificent mountains of Australia". These places contain some awesome rock climbing, no doubt, but compared to a real mountain range, they are lacking in scenery, height and bad weather!