You just have to keep looking, and looking, and looking. And be open to changing your mind from going in July to going in late August / Sept / Oct. Last year Iberia had deals to Paris / Milan / Barcelona for that time. But cheap doesn't exist the way it used to -- oil is up, flights are all minimum 1000 bucks it seems.
Sometimes there are flights out of Santiago de Chile for much cheaper than out of BA.
Also, check Copa/Continental airlines -- they occasionally have deals out of Cordoba instead of EZE departure.