Well, all the usual suspects are there - Haden, Dalkia, Johnson Controls, Trilogy, Carrier, etc. etc.
Plenty of tier 2 & 3 as well.
Ave. pay seems to be sound the mid $30's.
I don't know what you're T&C are like in the ACT. It'd be worth checking this out before you make your mind up. One thing I would suggest - there are plenty of toll roads around Brisbane, so make sure your employer has e-tags or provides a float to cover the cost. Around here, employers do not normally pay your travel time.