I flew courier 6 times: LAX-SIN. This was with Jupiter Courier. They had offices in LA and San Francisco. This was a good deal in the 90s. I flew for $200 or $400 r/t LAX-SIN. Airfare at the time was appox. $650 for this flight. All I had to do was give up my baggage space. They used it for their documents. Then they changed the rules and did not allow for stays over 30 days. Jupiter then raised their prices and it was not worth it. They then dropped the LAX-SIN route, started going to HKG. I went to Korean Air, then Eva Air. The days of getting cheap courier flights between most cites is over IMO.
Most courier companies fly between large hubs. New York-London, Miami-Rio, LA-Hong Kong. You should do some checking with courier companies, but I doubt there is anything from Canada to Europe. Couriers have been replaced by the Internet and FEDEX. Good Luck.