$500+ Roundtrip Canada to Buenos Aires on Air Canada
Argentina and Canada are two of my favorite countries, so I love this fare deal: Most major Canadian cities (Montreal, Toronto, Halifax, Vancouver) to Buenos Aires for as low as $511CAD roundtrip. Fares are bookable on Airfare.com
Update: SCL (Santiago, Chile also seems to work!)
YUL-EZE March 9-14 is $521CAD total RT. And there's lots of other dates from other Canadian cities.
These are more than half off - peak fares to Buenos Aires are often $1,000+. I've been to Buenos Aires many times before, including this past January, and absolutely love it. The weather there in March is that nice summer heat - 70's and 80's. If you are in Canada (or can position yourself to leave from Canada using miles) and have some vacation time to burn, this should be a no brainer!