Oh people ... this here is why we get overpriced games:
In the mid 90s, when 1 AUD = 0.65 USD, prices had to go up.
Then, when the exchange rate changed (a little), prices stayed high.
So people bitched.
Especially about the law against parallel importing that meant distributors for any product had a monopoly, and could charge whatever they wanted.
So, sometime around the turn of the millennium, that law was scrapped.
When things started going digital, the retailers saw that they couldn't compete.
So they bitched to the distributors, who bitched to the publishers, who turned around and price-fixed as many places as they could.
Fast forwards to right now, when 1 AUD = 1.08 USD, and prices have gone up even higher.
Some publishers, such as squeenix or thq, have very good prices on steam.
Others, such as activision and ea, are fucking twats.
So no. There is no reason why digital games are overpriced, other than protectionism.
But remember this. Despite the antiquated business practices of eb games, there are stores that will import games themselves, bypassing the distributors.
I go to dungeoncrawl (on elizabeth st, melbourne). To people who live elsewhere, dungeoncrawl's online store will ship anywhere. I think their warehouse is actually in nsw, so go figure.
The bottom line is, if you're paying $90 for a game, either on steam or in a store, fucking stop.
There are options, and you're just being an enabler.