With over 2,000,000 .au domain names already registered, it can be very hard to find a suitable unregistered cheapest domain name. Don't compromise on quality and consider the domain name aftermarket instead.
Domain Names can be valuable assets so if your domain is not being used to its maximum potential, why not look at finding your domain name a new home and possibly even profit from the sale at the same time.
The first stop if you're looking for a new domain name is to check whether it is still freely available for registration. Checking availability (even in bulk) and then registering a domain name is an very easy two minute job.