Welcome to the forum! The link below talks about flagshipcompany.com that gives you the best courier deals. A Canadian member here also mentions of a company in Toronto that drives the packages to the border and ships them through USPS or UPS US.
I'm not from Canada but I bumped into another forum on how to save shipping in Canada. It mentions of Link hidden: Login to view. You can checkout the whole forum thread here: Link hidden: Login to view