Sample date is for UA/LAN flights : Sept 27-Oct 1 $342 a.i.
UA to Mia then AA to Lima
On AA some of the flights are AA to Lima via Miami and Lan to Miami and AA back to IAD.

Sample Date Nov 30-Dec 3 DCA-LIM $338 A.I. All flights are on AA
Various dates available and various itineraries. depending on airport connections, you may be able to Knuckle the fare down a few $
Bookeable on Vayama and the big O and the gnome but not all the same dates work for the different booking engines.

Anyone who is booking on the big O and is staying 4 nights or more may want to book a package deal use promotonal code TRAVEL75VACATION which will save you at least $75