Ive had sellers send me stuff worth close to $800 before and never had any duty or taxes added upon entry.
Ok, to sum up: it sounds like a huge headache with a bunch of what ifs. I would rather collaborate with one of our Canadian based distributors and maybe motivate them to match my promotion once a month or something. Its not a big deal for an individual to go to USPS and send a package, but when FexEx picks up at the warehouse and I can print the postage online, its hard to justify the effort applied. I'll try to contact eShine and see if he would like to participate. Don't give him a hard time if he doesn't though because he is really not obligated to.
Just proposing a solution to UPS shipping here: If you open an account with them and declare yourself the broker, you only end up paying the Canadian tax of 5%, no other fees are applied. You just have to do the customs work yourself. That's what I do now. It would be nice to get free shipping in Canada from American vendors though