I don't want a free shoot; I think I was wanting to pay like 500 - 550 real to the model(s.) That is about 100$ so seems fair, I think - first time in Brazil so not sure what the average modelling rate would be.
The agencies that do exist in SP and Rio tend to be aimed for the fashion industry. I'm a hobbyist, not photographing for Balenciaga, so I doubt they would be interested.