Well, it's not easy to sign up for a plan in AUS for international student, unless you are AUS PR/Citizen
Normally they will require you to pass a 100-point ID check, by providing your:
1. PHOTO ID
2. Address proof
3. Income proof
Vodafone, Optus or 3 are the most popular provider
check out
www.vodafone.com.au
www.optus.com.au
for their price
Alternatively, you can buy Pre-paid sim card at any 7-11, convinence stores or their outlets and recharge anytime u want!
I am using Vodafone Maxi Cap with 2 years plan, have a Nokia phone for free!
參考: Myself, living in Sydney...