I had the same problem. I wanted to order Muscle Milk from the GNC web site. They sell it in Canada for $42 and it's being sold on the GNC web site on sale for $25.99. Funny it's so much cheaper there yet our dollar is higher right now (US$1 = CD$0.98). I went to the GNC store nearby and asked if they had any boxing day sales and they said no. I asked why the price of Muscle Milk went up from $39.99 to $42 and they said the price of protein has gone up... Obviously that is completely B.S. because they're selling it for $25.99 on their US web site.
I went online and did a search for other companies selling Muscle Milk and there are a few web sites in the US selling it for about $20. Why is it so much more expensive in Canada? I ended up buying four tubs of Muscle Milk from a company in the US for $20 each (the shipping for four tubs was $30). So when you factor in shipping, each tub cost me $27.50 so I still came out ahead.