For the consumable stuff and the OEM parts still available, I have found the local Honda dealer to be reasonably priced and often cheaper than distant on-line suppliers even when shipping is not considered - surprises me. You have to know your part numbers though because their computer system cannot look up older than 1979 (go figure). Parts are usually in the next day and it's close. Also, if you ask them, they will pull a big thick glossy catalog from under the counter, I think it is Parts Canada, and they can offer all sorts of third party parts for our bikes as well. Get to know the parts man behind the counter and they can help you. Shop when it is not busy for them and get their email address. Works for me.
But I have also bought lots of used parts on Ebay and Craigslist and Kijiji. I try to buy from other Canadians but there aren't that many of us with these bikes and the shipping is often a killer, especially for the bigger, heavier stuff.