Further to my last post, the prices have slightly increased at EB Games due to USD and AUD bs:

$20 USD - $28 AUD
$50 USD - $58 AUD

If you hear of it being any different please post a comment of updated prices.

Dont forget peeps that if you dont have access to a credit card to buy titles from steam, you can visit EB Games and buy a prepaid Steam card! There are 2 values you can get $20 USD ($23 AUD) or $50 USD ($55 AUD). They charge a little extra for the currency conversion fee.