look in the phone book under Audiologists, or Ear Care, or some such thing.
there were tons of places here in Vancouver, you just have to know that it's ear specialists that make musician's earplugs, not retailers.
edit: ah, i see you want the cheap non-custom-made stuff. sorry about that. i tried some ER-20's for a while (imported from US, really not that expensive) and they were ok, but nowhere near the quality of my custom ER-15's I now use. if i were you i would just bite the bullet and get molded plugs - you're still going to want them eventually anyway.