Hang in there Australia and NZ, things will even out over time.
This thread is a mirror image of Canada and the US during the PS1 & N64 days. I purchased WCW vs NWO World Tour for $109.99 when it was retailing in the US for $79.99. The Canadian dollar was on par with the US dollar, and it was straight up gouging. PS1 games that retailed in the US for $59.99 were $74.99-84.99 at around the same time. Even the N64 and PS1 greatest hits which retailed for $19.99 in the US were $29.99. There is simply no justifiable reason to have such a huge difference in price, especially considering almost %80 of the Canadian population lives within 100 miles of the US border.
The prices haev since levelled dramatically. The switch to all DVD formats certainly helped, as the cost of shipping the N64 cartridges added to cost, but now the price difference between the two countries is abour $5.00. That is understandable, the Canadian market is miniscule compared to the US or UK, so there is a need to cover fuel and shipping charges.
On top of that, the purchasing of US titles from US online retailers, and Canadians driving across the border to purchase games in the US itself drove the game companies to review their practice. If they couldn't gouge an extra $15.00 out of Canadians, they drop it by $10.00 and settle for gouging an extra $5.00. Eventually an extra $5.00 for the convenience of not having to order online or make a special trip across the border became generally accepted.
I understand the Aussie/NZ have fewer choices to affect change in the market, but increasing your online purchasing from retailers catering to your market is especially useful. It is tough to put pressure on the publishers from far away, especially when the politicians aren't helping matters, but spending your dollars online instead of at the local shops is one way to get them to change their tune. The video game stores want your money, and similarly if they see a huge drop in purchases, but the overall number of games being bought is staying the same, they will slowly change their tune.
It took from the NES to the PS2 to get competitive pricing in Canada, and I think the DD era can only help things along toward market equality.