Australia is under APNIC, which started rationing out its last /8 IP block in 2011.
Australia has a decent number of allocated addresses, around 2 per capita (compare with India, with 29 addresses per 1000 persons)[1], but presumably they will have to be reclaimed from existing users.
A newly started ISP in Australia could get a maximum of 2048 IPv4 addresses from APNIC. [2] If it needed more it would have to transfer them from another owner.