Are there really that many airlines in Argentina? I know of Aerolineas Argentina, LAN and Sol. And I suppose you can hop on the domestic leg of an international flight on Gol or Pluna, maybe. If there are other domestic airlines, I'd certainly like to hear about them.
Despegar.com, by the way, is a pretty good site and always lists a few package specials.
I would just recommend you globester.com if you want to book your cheap airline tickets & want to keep your travel budgeted. I will also suggest you don't go on words, just do the booking & see the difference yourself.