Just found this and thought folks might find it useful/interesting. It covers a variety of ways in which you can reduce your bill at Amazon and find better deals...from shopping in their hard-to-find "Outlet" to their likewise-cached "Warehouse".
I tried to see if most of the tips were valid with Amazon.ca as well. Some are, some aren't. Easiest way is to open separate tabs in your browser and change one to .ca for your searching. Most of these do not work in .ca but #1 does. Still, sometimes the American site still has a better deal than the .ca -- it's always worth comparing.
I point this out because it seems if I'm looking to make a purchase, sometimes .com has a significantly better price than .ca but, factoring in shipping and currency exchange, the Canadian site becomes a better deal.