As much as I hate to encourage Yatango and there really really really lame adverts on foxtel (https://www.youtube.com/watch?v=hQhO3C-26ms) Free is free!
Was on Spotify. They run on Optus 3G.
Rates appear to be a bit dearer than amaysim, but if you're just after the $10 sim for one month then I guess this is for you.
***Buy a $10 Prepaid SIM today and receive 1000 Voice Minutes + 1000 SMS + 3GB Data for FREE, with our 30 day Yatango trial offer***
**Stop paying for more than you need on your mobile!**