an average taxi ride will be about 90 minutes each way, and could total about 300 reals roundtrip. 

while by bus, average travel time is about 120 minutes each way, at a roundtrip cost of about 30 reals per person, depending on the buses used.     

getting to this part of rio via bus can be a bit complicated for visitors who are not familiar with the city, or not fluent in portuguese - a personal guide or assistant is always a great idea.