[wavelandscott (Scott)]

I can't speak about GST/Duty etc...

But don't also forget that...

Assuming that your credit card is an Australian Dollar denominated one that they will charge you a conversion fee of some kind (they may hide it in a poor exchange rate figure or it may be an additional fee)...

So you do yourself a disservice in calculating the cost if you use the "official" exchange rate...better to look at what Travelex (or similar) are using to calculate your AUD$ cost...