Indeed, it does happen. Check out the link from Melhores Destinos for a sale back in August: ~U$300 (plus taxes) on SAA from SP. IIRC there was also a very good sale by LATAM when they inaugurated the route.
South Africa is a great country, and one of the few where our poor BRL stretches quite far these days!
http://www.melhoresdestinos.com.br/p...-africa-do-sul
For other destinations in Africa and Middle East, Ethiopian Air often has good deals. I believe they stop in Lome (Togo) on the way to Addis from SP, but you wouldn't be able to connect from there. Plenty of connections from Addis though.