Not intended as exhaustive and suggestions welcome.
USydney, UNSW and UTS in Sydney all have Economics Schools with several staff working on behavioural topics. Ditto the College of Business and Economics at ANU and the Economics groups at UMelbourne and Monash. The Queensland Behavioural Economics (QuBE) at the Queensland University of Technology has an active research group.
The Society for Risk Analysis has an Australian and New Zealand branch
The IAREP country representative for Australia is Brad Jorgensen
Sydney Morning Herald article on the New South Wales version of the UK Nudge Unit.
ASIC, Australia’s corporate, markets and financial services regulator, has released work recently on behavioural economics.
There is a behavioural economics meet-up group in Sydney that I found very well-attended and useful.
Recent Australian radio debate about behavioural economics in particular nudge.