Lan Chile is the only bird that flys this route--and only on certain days of the week. Some travel agents might be able to offer better deals in chile but since there is no competition on this route, I doubt any great deals exist.

The only ways that you might be able to save a bit of money is to incorporate the trip to Easter Island with your ticket down to chile and you also might want to see if Lan offers any air passes that give a discount to Easter Island.