I have no idea about MAC (might want to try and post in there), but UNSW's Uniwide does cost you.
$1 to login (charged max once per day), then 10c per MB downloaded outside of UNSW. There's discount rates for sites within Australia, such as AARNet. If you do a CSE course however, like comp 1A, CSE gives you funds in your UDUS account which you can use for Uniwide.
CSE wireless is free, but any data used comes out of your regular CSE account IP usage.