VentraIP Australia is currently offering $1 .org.au domain names.
Applies to new registrations for one year .org.au domain names have an eligibility requirement that you will need to meet before you'll be able to register one. Typically domain names over at VentraIP in the .org.au namespace need to be manually checked for eligibility and approved.
For eligibility requirements see the right-hand side of the page on VentraIP's website.
Pretty damn sure that .org.au is reserved for Australian registered charities so good luck with that.
*and non-profits.