Found 15th Jan 2018
Currently $15.99 cad but $9.99 with ps plus. To buy at ps plus price: follow steps to set up Canadian account and buy Canadian top up voucher from pcgamesupply. Before purchasing, start any multiplayer game using your Canadian account (make sure to deactivate your uk ps plus account just while you do this step, or the plus subscription will carry through to your Canadian account). On starting a multiplayer game, you’ll be offered a 2 day free plus trial. Accept, and return to the store where the price of Witness will change the $9.99. First post so go easy! Hope it helps someone.