FLIGHT INFORMATION
From Windsor:

Try Detroit to Bellingham, WA.
Click HERE to find return flights from 381.50 US.
From Toronto:

Try Toronto-Abbotsford as well as into Vancouver. (Sometimes there are sales.)

TANGO flights from 600.73 Cdn.

WESTJET flights from 602.87 Cdn.

JETSGO flights from $552.58!
From Elsewhere:

Check out the TANGO, WESTJET, and JETSGO links, above.

Also try these links:
Cheap Airfare
Travelocity
Expedia