I can't be sure, as there is no US or AU prefix in front of the price. The current price in the US for US dollar cruises is $29US, but I don't know how your card will be charged if you pre-purchase. $AU29 would be a bonus if that is the case, and your best chance to snag a bargain if you are charged that way. I am not game to click one button to many to see if it shows differently in the shopping cart.
I don't think the app has the ability to handle 2 different currencies, and the ship is currently operating on US currency, but I expect they will change to $AU40 when the ship arrives here and changes to our local currency onboard.