Argentina is not as cheap as it once was, due to the continued inflation that plagues the country each year. I recently picked up a Lonely Planet at my hostel from 2004 which listed that for every USD$1 a traveller would get ARS$2.9. Nine short years later and that number has more than doubled as USD$1 will get someone around ARS$5.33.
Exchange Rate in Buenos Aires
Photo from Gringo in Buenos Aires
The catch is that the ARS$5.33 amount is the “official” Argentinean exchange rate but the number changes drastically on the black market. In Argentina the US dollar is almost impossible to find (forget trying to take out USD from a bank), which has prompted many individuals to start their own exchange businesses, offering a much better rate than the banks. As of June 14 2013, an exchange on the black market can garner you ARS$8 (or $8.5) for every USD$1 – if not higher. Here are some tips to get the best exchange rate in Buenos Aires
Tip 1: DO NOT exchange money at the airport. The exchange kiosks in the airport often give you an even LOWER exchange rate than the banks. It is wise to bring some extra pesos with until you are able to exchange more money.
Tip 2: Bring a decent amount of USD cash with you to Argentina so as to avoid using bank cards and/or visas in the country. When using “plastic” not only are you paying a lower rate but you also have extra charges (such as the withdrawal feel) that are getting applied to your cards.
Tip 3: If you do not know any Argentineans, just ask around to find an exchange place. If you walk down Avenida Florida you probably will hear many people screaming “CAMBIO” (which means exchange). Please be careful with these exchange houses as they might try to rip you off, especially if you don’t speak good Spanish and you are a tourist. If you do decided to exchange money with these individuals than don not be afraid to haggle. You should always haggle. 
Instead I would recommend asking more reliable people first, such as hostel/hotel workers or your tour guides etc., to find the best place to exchange money (practically everyone one does it!). My friends exchanged their USD with their landlord when they first rented out their apartment.
Tip 4: If you run out of USD don’t fret! Uruguay is a short 1.5 – 3 hour boat ride from Buenos Aires and can be easily done as a day trip. In Uruguay you can easily take out USD to take back to Buenos Aires. There is another option if you run out of dollars while in Argentina.
Tip 5: There is a service called XOOM that will allow you to transfer money from your bank account overseas and will exchange it at a rate much closer to the “blue” rate. Be advised that there is just one office in Buenos Aires and the wait time can be long. Online sign up is quick and free and the money is usually available for pick up within the hour. XOOM works with the company  “]MORE[” for money transfers, so you will pick up your money at a ]MORE[ store, not Xoom.
Tip 6: It is best to bring USD (even if you are not in American) but many places also exchange British Pounds, Canadian Dollars and Euros at good rates.  
I tried to explain the system to a friend of mine who was taking out money from her bank account each week. She had come to Buenos Aires without USD and I had told her that it was smarter to head over to Uruguay so that she could save some money. For example my friend takes out ARS$1000 each week which is USD$187.75 (at the ARS$5.33 : USD$1 rate). That same amount USD$187.75 exchanged on the open market would garner my friend ARS$1502 (at the ARS$8 : USD$1 rate). As she takes out money each week at the bank she is losing a MINIMUM (if she takes out more she loses more) USD$93.88.