I live in Ottawa, Canada. The rubber washer (ring) for my blender is so old and misshapen that it doesn’t seal any more. The rest of the blender is perfectly good, so I don’t want to buy a new one, just a new rubber ring. They seem to cost about $1 online, but shipping is more than that and I can’t find a supplier that will ship to Canada. My blender is a standard blender (i.e., fits Mason jars) so I think any “brand” of ring for a standard sized blender will do. Aside from buying a used blender at a second-hand shop and using its ring, where can I buy just a ring?
(answers that allow me to replace my rubber washer honestly preferred)

buy a new one take the rubber out then return w/ the old one.
either go to hardeware store or go on line to the manufacture they;ll help you get one
I work in a machine shop that repairs hydraulic and pneumatic cylinders. We frequently sell replacement gaskets to home owners, for their blenders, faucets, garden hoses, etc., that are also used in these cylinders.
If you find a suitable gasket on a new model, and if that manufacturer ships to Canada, you should be able to order it from them as a replacement part.