Select the lowest price in the list of sellers.
After changing currency to AUD the total at checkout is
$4.70 $3.84 $5.11
No VPN needed to purchase the code, but you will need to be connected to a VPN with location set to Argentina to redeem (for something free I'd recommend TunnelBear). May also work with the free VPN in Opera browser with location set to Europe.
Credit to Slickdeals.