Latam Airlines, a One World alliance have round trip airfares travelling from Orlando (MCO) to Sao Paulo Brazil (GRU) for $589, making 1 stop. Saw this on Scott's Flights.
Departs MCO: Aug 2, 9-13, 16-18, 20-21, 23-28, 30-31; Sept 1, 3-4, 8-11, 13-17, 20-21, 24, 27; Oct 8, 18-19, 22-23, 25-26; Nov 2, 8, 15, 22, 23
Returns: good availability returns, generally a 7 day stay works
This only prices out via google flights. I'm not getting it to work with OTAs or Latam directly. So go to google flights [google.com]
for these two cities and pick your dates, book your flights from there. Looks like outbound flight will be nonstop while inbound flight may be a long stopover or even two stops.
HT: Scotts Cheap Flights