Additional charges are out of the control of TB as they are tacked on by UPS based on duties and brokerage fees. I have tried to look at what gets charged (NAFTA and other duty rules) and why some shipments are and some aren't, but I couldn't find a clear answer. It sort of seems like a black box to me.
Based on my experience with two shipments this fall, I would expect to add on about $60 to an order - $30 shipping fee charged by TB and $30 or so due on delivery to UPS. I don't mind paying a premium for quality (especially if it is going to the company making these high-quality goods that I get tons of use and enjoyment from), but those extra charges are certainly steep enough for me to keep me from ordering as often as I would otherwise, especially if our dollar is slipping.
I would love to see cheaper shipping options offered. I would also be happy to combine orders to Canada with anyone in Manitoba or NW Ontario. Failing that, I will save my pennies and limit myself to about one order per year while drooling over everyone else's pictures.