There are other costs to doing business in other countries that we don't have in the U.S. For example, worker rights are much lower in the U.S. than other industrial countries. The workers in the U.S. get less paid vacation and maternity leave, for example. Also import duties might be different.
Finally the revenue stream from iTunes from the sale of each iOS device is much lower outside of the U.S. than it is in the U.S. The U.S. is also a place where there is added value in capturing market share. Most of the software used by the rest of the world is made in the U.S. The market share captured by iOS so far in the U.S. is actually one of the huge advantages that Apple has. I'd say it is THE MOST important factor right now. Developers develop for iOS first and possibly only. Android and Windows are both secondary considerations. This is huge fact.
Another reason is that Apple builds in a buffer for currency fluctuation because once they announce a price for an item they never want to increase it for the same item. Obviously when extreme moves happen, Apple will make a price increase. But this is another factor.
So I wouldn't say Apple is "gouging" foreigners. But yes prices are higher. I have friends who when they travel home often travel with iDevices as gifts for their family. So I know this is a real issue. But there are lots of factors at play.
