Argentina is one of the few countries where you absolutely should not swipe a credit card or withdraw cash from ATMs but rather bring crisp $100 bills with you.
This is because Argentina doesn’t allow its currency to float freely and tries to keep an official exchange rate that you cannot use to convert local pesos to USD. This has created a massive black market, and the unofficial exchange rate is called “Dolar Blue” or blue dollar.
You can currently get roughly 110 pesos for each USD if you use an ATM, but close to 200 if you use one of the “unofficial” exchange houses.
You just need to go to Calle Florida, and there is practically someone every couple of meters yelling CAMBIO CAMBIO.
You should be clear how much you would like to exchange, and $100 is in the highest demand. I negotiated last week 199.5 pesos per USD for the $100 bills that I had.
These exchange houses are always in one of the nearby buildings, and you enter one of the offices.
I didn’t take any photos inside, but usually, there is a window with a cash counting machine. They count your dollars, and you get stacks/bundles of pesos. The largest 1,000 ARS note is currently worth roughly $5.
Previous Blue Dollar Coverage:
You save today 45% on the prices in Argentina if you bring $100 notes, do the black market exchange, and then pay. However, the savings at hotels are a bit less because the VAT is not waived for cash payments like those done with credit cards.
The USD-Peso rate was roughly 1:3 when I was in Argentina for the first time in the early 2000s, and now it is 1:200.
The value of Brazilian reais has dramatically fluctuated over the same period, but the government, unlike Argentina’s, has not tried to control how much people can exchange.
You can also exchange other currencies (I head euros and reais accepted too), but I would assume that you get the best rate for $100 bills. Just make sure that you are familiar with the Argentinean notes so that you won’t be given fake ones.