I just scored what I consider to be incredibly good fares within South America.
I got 2 x Economy tickets: Santiago (Chile) > Guayaquil > Baltra (Galapagos)> Cusco for just under $1300 (so around $650 each). Considering how expensive flights usually are within South America, I'm pretty stoked.
Flights just to Baltra (via Guayaquil) alone are $568 (on the same day, so I'm essentially getting the flight to Cusco for $82. I'm not sure why, but it looks like there are extra discounts when you go multi-city.
20% discount is valid for travels within destinations in South America in Economy class. Sale is exclusive for LAN.com and must be purchased by 17 April 2015. Discount will apply at checkout (step 3).
Purchase your tickets with an exclusive 20% discount in LAN.com in all flights from Australia to South America, and all regional and domestic flights between Santiago, Lima, Buenos Aires, Sao Paulo and more! Fly from 1 of May to 30 of November 2015.
i've heard it's cheaper to purchase flights using a VPN in said country.
I've never done this myself though.