It's baaack!
Approximately $20 Skype Credit is selling for $10 at the website at the link.
Contrary to what the name of the site implies, there is evidently nothing preventing someone who is not a student from taking advantage of this deal. You do not appear to need an .edu email address.
This is supposed to be a "deal of the day" sort of thing (as it has a timer), but when the deal was last active, they apparently extended it several days, so I don't know if that is the case now.
Because the deal is in US dollars and requires conversion at Skype's rate, the actual value you will receive is slightly below AUD $20. YMMV.
People are reporting success buying multiple vouchers by using multiple CollegeBudget accounts.
However, be aware that Skype has been imposing a 5-voucher limit on use of this particular voucher in a single account.
That means that the maximum amount that can be deposited into one Skype account using this deal is $100 (minus exchange rate vagaries.)