Another choice is to buy a Brazil Airpass where, if you live outside Brazil and you fly into the country, you can fly anywhere in Brazil for $100 a flight. Several rules apply, so check it out closely. Minimum purchase is $300 for 3 flights in 1 region of Brazil and $500 for 5 flights anywhere in the country.
My family did the $500 pass and it became a very cheap way to travel around Brazil. We flew ATL - GRU - Porto Alegre on Delta (and TransBrasil which was a DELTA partner at the time). We left Porto Alegre and flew to Iguacu Falls (changes planes in GRU), Rio de Janeiro, Manaus, Salvador (changed planes in Brasilia), and ended back in GRU to catch the DELTA flight back to ATL.
Hope this helps.