For those out of the loop and don't care to check, Argentina and Turkey have had very volatile currencies for years now. Developers had to constantly update the pricing on those countries because the currencies keep losing value. So Valve decided to ease the burden on the developers and let them set the pricing based on the USD. That price then get converted to the local currency based on the exchange rate. When the exchange rate is 1 USD to ~800 peso it's no wonder that game prices are insane.
It's higher now, more like 1 USD is around 1200 (black market rate, the 'real' value) The problem per se is not that the store is in USD now, but that during the transition many games abandoned regional pricing and set their prices to the default, which is the american value. So for example the game Jedi survivor is now listed at USD70, and with taxes it comes around to ~USD110. I'm working full time as an accountant, and that's a third of my monthly salary, which is completely unaffordable.