I've had the same experiences as Jason and casey01 re: Monoprice. I've used them many times over the past year, prices are incredibly low, quality is good, delivery time is a week or so (to Burlington, ON), delivery costs are low, and duties are low to none.

I've also used these guys http://www.infinitecables.com/index.html
Their prices aren't typically as low as Monoprice but they are in Ontario (Markham).

Bob