GameStop / Impulse Driven are having their usual weekend sale with many titles under $10(USD). Often the sale games are region restricted and not available in Aus but this time there seems to be quite a few available.
This game is the current Steam weekend game deal with 75% off but the Steam price for this Augmented Edition is $11.24 (USD)
These Gamestop deals usually run for the weekend only so go have a browse at the other stuff too.
EDIT: This is a steam activation key game.
Good price. Thanks OP.