Total War: Rome II: US $29.99 @ Amazon [Download]

Works out to around AUD $33. Amazon allows unlimited downloads (on computers you own) once you've purchased.

The description on amazon says "available only to customers located in the United States and who have a U.S. billing address".

The workaround for this is to add a random US address to your credit card. Remember to use a state like Delaware or Oregon who don't apply state-based sales tax.

I used a 28 degrees credit card to minimize foreign exchange fees and simply used 123 Fake Street DE.