Broome, Perth, whatever. As long as it is in the Northern Territory nobody cares.

There are only two choice on this route (DJ and QF). DJ currently charges $219 one way (plus a few fees) and QF $275 (all incl).
You could also consider Tiger but this requires a connection and you fly to the Gold or Sunshine Coast, not Brisbane.

I would just wait for a QF Sale to happen and then you should get the QF flight for almost the price of the DJ flight. The advantage is that you will get FFP and when you combine this with Woolworth Shopping and a good credit card you will have enough points to upgrade to business class once in a while. And this is a good investment on that route especially when on the red eye.

The other advantage of QF is the equipment used. DJ flies there 738s while QF has a 763. Much nicer and roomier on such a long flight.