Ugh, yeah same. I live relatively close to the border with family on the other side and could potentially receive them in the US, take them across and do Canadian distribution but I'm not sure how much would be reasonable to charge for shipping because I've no idea what it costs to ship things up there. I would assume it to be fairly similar to US pricing but I don't want to make that assumption. However the primary reason I haven't said anything thus far is that I don't have a regular schedule of when I go up there and it probably won't be till around American Thanksgiving. From your last post I glean that you will cover whatever the cost is to me or the other guy to have us ship them out and then bill accordingly, but if you collect the money in advance without an accurate quote on Canadian shipping that would be dangerous for you and I wouldn't like to see our kind organizer of this group buy in that position. Also it would only be fair to only charge the Canadian addresses more than the original estimate and not raise the prices for everyone... I dunno.
You could also send out invoices and in it write that they must include their shipping address in the comment of the payment and it must be a US address, otherwise they must notify you that you must be taken off the list. I'm guessing you contacted them via PM and I suspect most of those who haven't responded aren't regulars here who haven't come back to check their PMs or the thread and are just waiting for an invoice.