Brand name drugs are cheaper in Canada than the US, and, of course, if there is a generic version in Canada, that will be even cheaper than US brand names. They do require a prescription. I think many Canadian pharmacies will honor prescriptions from US doctors--I think that they must rewrite them. Since Victoria is full of American tourists, there must be pharmacies there that would take US prescriptions, but some of them might not mail to the US.
You don't have to go to Canada to use a Canadian pharmacy. I use Jandrugs, which is in Winnipeg, even though I've never been there, because someone I know had used them. I think it must cost more than alldaychemist, but I stick with them because they've been honest and reliable. They also sell generics from India, which are even cheaper than Canadian drugs, and seem to work as well. You can Fax the US prescription, or scan it and email it.
Here's a map of pharmacies in Victoria:
There are a bunch in the central area, you can get off the ferry, and stop by the pharmacy on your way to the Empress Hotel for high tea.