How much does it cost to register a .com.au domain? It can be $140/2 years from MelbourneIT, or you can register one at Solidinternet for less than $20/2 year. They claim to be "Australia's cheapest .com.au .net.au .org.au" however for .id.au they are more expensive.
It is selling under AusRegistry's wholesale price I think so I am not sure how they can make profit from it but I guess it is not my problem :)
Disclaimer: sorry no personal experience with Solidinternet. Just somehow found them to be the cheapest.
The price looks good. I think last time I looking for a com.au domain, the cheapest one is ~$40.
But afaik, you cant register a com.au unless you have ABN?