cheap airfares within South America?
 

Does South America have budget airlines like RyanAir and Easy Jet? or does anyone know how I should go about booking (cheap) flights between say...Lima and Rio?

Well, there are no cheap air companies like in Europe, but lucky for you, since you're going to Brazil you should check out Gol Airlines. They are very popular these days and are known to have some of the cheapest flights in the area... (Buenos Aires - Santiago is a LOT cheaper now if you fly with Gol).

So I'd check them out!!