After exhausting all the usual suspects, I called Marble's Gun Sights and spoke with the customer service manager. Took several tries as he works four 10 hours days and goes to a lot of meetings.
He told me they don't sell retail and I'd have to order from a dealer. I told my frustrations with that ("We don't ship to Canada", It's on back order,", etc., etc.) and he sold me what I wanted.
It pays to go to the source.