Put up an ad on LocalBitcoins.com. You possibly might find a tourist arriving with bitcoins who is looking for Argentine pesos. Or perhaps you'll find a local Bitcoin miner who is simply looking to cash out some bitcoins for your pesos.
Are there any goods that you could pay for with your pesos and then have the goods shipped to a buyer who pays using bitcoins?
You might laugh, but you might find buyers for Argentine pesos sent via the mail. If there's a market for the Zimbabwe 100 trillion dollar note, there's probably buyers wanting a set of your paper banknotes (for novelty, or maybe even speculation -- who knows.
Again, travelers are a resource for you. For instance, even while visiting a foreign country a traveler might have family or friend back home that would be able to deposit cash for the purpose of buying bitcoins. The typical traveler might not need this, but if for instance, the traveler wants to buy a larger valued item and the seller only accepts cash then the traveler is in a bind. You are simply helping the traveler convert paper money (e.g., USDs) in one country for a different paper money (ARS) in another.
You might also follow the Spanish board on BitcoinTalk forum to find others who might wish to trade by selling bitcoins to you. Or find some Argentine merchants who accept bitcoin (like this, this or this) and see if they have coins and are looking to trade. Or find a merchant that does a lot of export and convince that merchant to begin accepting bitcoins. When they do, you've found your supply of coins.