Very happy to share this badassity: For two return tickets, total out-of-pocket: $630 CAD. Normal price would be over $2000 for sure, since we are going in high season. Note that this includes a 2 day stopover in Santiago, Chile to visit some friends, so it's really 3 separate flights not a return.
How'd we do it?
Well, on our last vacation the airline overbooked our flight, so we happily took a different flight that delayed us only 3 hours, and each got a voucher worth $500. That's $1000 off.
Also, the airline has sales periodically, and we've been watching the prices for months (need to use the vouchers with this airline). Finally they had a sale for when we can go, this November - price went from $1600/ticket down to $1130/ticket. DW caught it the day it changed. Because the vouchers were being phased out we couldn't redeem them over phone or internet, had to go to the airport and buy them there directly. That night I went (took public transit, cost $5), lined up and finally got them all sorted out. Gladly paid the $1130*2 - $1000 = $1260 (done in 2 separate transactions of $630).
Then, using our rewards credit card (Capital One Aspire Travel, basically gives 2% cash back to use on any travel) I was able to redeem all my points to just barely cover one of the $630 transactions.
The challenge now is to make the trip as enjoyable as possible given the 3 weeks we have and not spend a ton. The country is so big, it's going to be hard to get around. But we're staying with friends in Chile and family in Argentina, so it shouldn't be too bad. Just wish we had more time to spend there, but then that's the main reason we're working toward FIRE :)