Hello Paul
Its the brokerage fees and taxes that will up your shipping costs quite a bit when using couriers. Try to get small items mailed when possible. Like Kevinski said, I use an outlet in Port Huron to pick up packages.
I find trying to find parts on this side of the boarder to be a painful experience. I just bought shocks from the US for my 57 Olds for $22 each when Carquest wanted $49 each. Most times the guy behind the counter has no way of looking up the part let alone get it.
Good luck with your build.
Mark