Currency paid and points of sale are not the same. Often intl fares are different based on certain fares being made available for purchase in 1 country and not another, and they are not related to the currency paid.

Is the OP's question "can I pay in a different currency?" or "Can I purchase a fare that is targeted for a particular point of sale from a different country?"

Currency is converted into NUCs (neutral unit of currency) and then an exchange rate is applied to price in a different currency. A NUC is basicly the US dollar. http://en.wikipedia.org/wiki/Neutral...tion_(airlines)

In much the same way that almost identical (sometimes small variactions) of cameras and electronics retail for different prices in different countries, with the prices differing by more than the exchange rate and any addl tariffs applied for importation, airlines sell tickets the same way, supply/demand/competition. It isn't just the booking code, advanced purchase, seasonality/blackout dates,a nd min/max stay that determine a fare, but also the point of sale.