How would that work? If I understand correctly the CPF number needs to match the passenger details. So someone else could buy the ticket for you, but then the ticket is in their name.
I can confirm that that's how it works. The CPF number is needed from the person buying the ticket, not the person travelling.
Nevertheless, I don't see such a brokering business being very profitable. The main problems are (a) the customer doesn't care about the extra cost because his/her company is paying or (b) he doesn't even realize he's being suckered because he used the English-language TAM website and didn't realize Brazilians get a better price.
[1] http://brazilsense.com/index.php?title=Booking_a_domestic_fl...
The real problem for me was paying with my US bank card (w/ Visa or Mastercard symbol). Because this wasn't allowed, I had to travel to the airport and pay in person on several occassions.