Not sure how it would affect the site's ability to collect on the referral, but if you go through the link here, copy the item number, and paste it in ebay.ca, you should be able to access it just fine. I know I have done that with several items that Canadians have posted links to and it works the other way around for me.
PS: The site may only be able to benefit from US only ebay purchases.
-- Dan --
Note: Please see my profile for more info regarding trading (section updated 3/4/2024). I have added a large portion of my inventory to the site, and currently have trading turned on (details are in my profile).