The regional price fixing on Steam is frustrating; my general way of dealing with it is to not buy a game until it's reduced to nearly nothing and make a complaint on the Steam Facebook feed.
In any case, it's funny when there's a loophole in the price fixing, where the game is available cheap by getting it through a package that isn't marked up for the privilege of living in Australia. On the Steam sales today (10/07/2011) this happened with Dead Space 2:
Buying the game on its own, with the 50% discount comes to a total of $35USD. But if you buy it in a bundle with the original Dead Space, it comes to $20USD. You can save $15 and get an extra game too!