Amazon.com has the
10lbs Optimum Nutrition Gold Standard 100% Whey for $65 with the Subscribe & Save discount
http://www.amazon.com/Optimum-Nutrit...3916640&sr=8-2
Amazon.com doesn't ship supplements to Canada so you're going to have to have it shipped to Blaine or Point Roberts and pick it up from there.
I think since whey is a consumable that there is no duties and no GST