http://www.kayak.com/flights#/YOW-KT...04-24-flexible
A few dates in April are going for as low as 383$. You can try to play with different dates combinations for other opportunities.
[edit]Stops are in Chicago (or Detroit) and Seattle. I assume if you would prefer to go to say Seattle only, your ticket would get voided for the return since you did not complete your initial itinerary?
Just noticed my currency was set to US dollar, make it 391 CDN.