Hello!
We are staying at the Samba Palace hostel, not tat close to the beach but great reviews - worth a look. Good luck! x

i think there are still hostel beds to be had in Rio and Sao Paulo.....you just have to be super flexible, and willing to pay a lot more for something that wouldn't normally cost that much.
i'm a solo traveler and i got a dorm room that sleeps 10-20 people. it was 200 Reals a night for it, but its right in the middle of Copacabana. it'll be worth it.

200 reais per night is standard rate for Carnaval/NYE. So its standard price for most hostels. The further from the beach you are, the cheaper itll be.
Also, its reais as a plural. No L.

Hi, myself and my girlfriend are going to Brazil for the World Cup and we've just booked into a guesthouse which still has some vacancies available. It's excellently located, here's a link to some info about it: http://realbrazilaccomodation.com/rio-guesthouse-accommodation/
Hope that helps :)