Australia was historically a smaller market that is physically far away from America and ( and had fewer trade links with Japan). Australian TVs were PAL while America and Japan used NTSC, which added a whole other layer of complexity. This meant that PAL production lines were geared towards the European market, with Australia getting the excess. Those copies then had to be shipped across the Pacific Ocean, which is expensive. Combine a smaller, lower-priority market with longer, more complex shipping, and manufacturers charged more to make a profit. This set a standard price for Australia which persists even today.

Regional pricing will always be complex and never fair for one group or another. Consumers in one region with high purchasing power will be charged more so that consumers in other regions with less purchasing power can be charged less.

Otherwise vendors would completely price themselves out of certain markets, denying a potential revenue stream and potentially opening avenues for local competitors to crop up.

It is hard to do direct conversions because cost of living is complex and some store fronts don't include all taxes where in Australia you must show the final buy price. Valve has always had gripe with Australia because we kept fining Valve for not following our consumer laws and forcing us to buy everything in US$ but that has now changed.