I think $US40 which is about R65 is a very good price for a taxi between GRU and CGH. GOL, TAM and Webjet have free bus transfers as does Diners Club for its cardholders. The Airport Bus Service that also has buses to Republica and Paulista is about R30. Local bus/metro/metro/local bus will cost around R10 if you are adventurous and have plenty of time