Señor Ambassador, you have two different issues with having/getting money here.
I can't really speak to purchasing real estate here - if you are here as a retiree you may not have some of the complications that a lot of others have in proving origin of funds, paying taxes on the money, etc.
You may have few to no problems if you are talking about bringing in monthly retirement payments as well. I'm not sure about that, not being retired and my residency being based on my marriage to an Argentine resident.
But as far as anything over and above your monthly retirement stipend (what officially comes in to Argentina), there's only one real way to get the money in here without paying through the nose or bringing it in (either yourself or someone you know): black market. That may consist of knowing a cueva - black market cambios, or white market guys who also work in the black market. Usually these places trade in currencies and bonds and such at the level where they will do transfers from outside the country. As mentioned by someone else, you wire money to them in an account outside the country and they give you dollars (or euros, or maybe even reais), or pesos at a good exchange rate. They charge a fee - in good times maybe 1%, now a lot of places seem to be charging around 4%, with a minimum of something like $100 USD fee. So the good exchange rate isn't all that good when you get finished, but you can get large chunks of money down here, and better than Xoom or other commercial places. Not to mention places like Xoom take your personal information and AFIP could become an issue - the cuevas don't "know" who you are.
Or, you can find a local business or person that has a need to get their/its money out of the country. This is similar to a cueva except it's a deal between friends/individuals. If they have dollars (I know some places and people that buy dollars with the pesos they earn so it doesn't lose value) and then make a deal like this where you would send a wire to their bank account and they give you the money here. Or, if they want to go direct from pesos to dollars in their overseas account, you usually split the buy/sell price on a pre-determined website that tracks the blue dollar and they give you your pesos here.
It takes some time to find these methods usually. Obviously, working in the black market can be problematic and these people don't just advertise on the street, but rather by word of mouth.
