$549 but located in Perth -
BlackVue DR650S-2CH In Car Camera | Radars Direct Australia
Alternatively just chuck the model number in ebay.com.au and there will be sellers over east that offer them for $499. Just depends if you want to spend an extra $50 and pick it up in person immediately.
Not sure of anything comparable to be honest. Just a warning, the rear camera is shit - 720p. It's good for a second view to prove you weren't at fault in an accident, etc. but very hard to get a numberplate from unless the light is perfect.