I did a search JFK-YYZ for February and found TAM $64 one way in Economy or $102 in Business (Feb. 12)
Don't know if there are other dates available (but last year there was a similar sale, during February-March-April, and again in May-June IIRC)
(found on JustFly.com - On Cheapoair.com it's $67 for Econ)