In Mississauga you have Rider's choice, Cycle World West (on wolfdale), by 400 & steeles you have Kahuna Powersports, out west of Oakville you have Burlington Cycle.
There is a Honda Powerhouse in Milton, and I believe there is one by trafalger & QEW. They have 500ml bottles for about $10, which is fine since a 1L bottle of aftermarket is about $20.
There are tons of brands out there, any are fine. Honda, Yamahalube, Belray, Motul, Amsoil, etc. There is actually no standard for fork oil weight so every brand on the market is different (10 weight across every brand is not actually 10W), I made the mistake of delving deeper into that discussion and regret it now... unless you are racing, the brand of fork fluid won't matter to us normies.