Yikes - that sounds high. I can't recall exactly but I think I either used AAdvantage miles or, alternatively, you should look into the OneWorld South American pass through LAN.
IIRC, you'll need at least 3 legs - you can add on a throwaway segment that's really cheap and you might end up with a lower fare overall.
The nice thing is that the fares earn miles and they a fairly high fare class so they can be changed pretty easily.