Lets take a stock GTX 680 for example. Cost price on this card should not be $499 for Australian distributors.
I believe the problem lies in the fact that in the US, EVGA is the only distributor for their cards, so Newegg/NCIX/Tiger/etc all buy from EVGA.
Whereas in Aus, a separate distributor buys from EVGA, and then PCCG/CLP/etc buy from the Aussie distributor who is bringing up prices due to handling.
After quite a bit of searching, it seems like there are two distributors in Aus for EVGA (places where PCCG/MSY/itsdirect/CPL/etc buy their stock from). Ingram Micro
Now working in retail, products have anywhere from 70% - 7% margin with 25% being the average.
Please note the below is *not* based on fact.
Lets say that in the US EVGA sell the GTX 680 to resellers for $399 giving Newegg/NCIX/Tiger/etc around a 23% profit margin after shipping.
EVGA would sell the same card to Ingram and MMT for the same price, because there is no reason for them not to. EVGA are making the same amount off the card, but MMT & Ingram would be making a bit less due to higher shipping costs.
In a worst case senario, (if MMT & Ingram have a crappy deal on their shipping) it costs them $50 per card shipped to Aus.
Now MMT & Ingrams cost price on the card is $549.
As these companies are in the buisnees of making money, they then sell the product onto MSY/CPL/etc for a profit. Lets say they decide the want a 15% cut to make it worthwhile which brings the cost price up to $631.
At this point, retailers would only be making around $55-$65 when selling the card at $699 which represents roughly a 9% profit margin.
I hope this has shed some light on the subject, even if it is all hypothetical.