Are you brave enough to use Priceline? I just looked at bidding for travel and Brazil now does Priceline rooms.
3 and 4 star hotels are around $120 to $160 and the two hotels won so far at that price is the 4 star Rio Intercontinental and the 4 star Sheraton.
After reading the posts, someone mentioned that the Marriot is also in the hotel mix but no one has posted if they have successfully bid on it yet.
Here is the bidding for travel forum, where they are talking about the Rio hotels and what they won them for.