I booked this trip for next April about a month ago. It was 35,000 miles + $119.00 in taxes/ticketing fee. We are simply passing through Lima en route, so we were able to get the connection for 5,000 miles instead of 10,000. Not sure what your itinerary is going to be, but we have to get there early to acclimate to the elevation before tackling the Inca Trail to Maccu Picchu.

Our route is DFW-MIA-LIM-CUZ

EDIT: I second the advice to go all the way to CUZ on the award ticket. It's an 18 hour drive from Lima, there's no train out there and airfare was an average of $500.00 roundtrip between LIM-CUZ on Taca.