Pyrex isn't super hard to find out here in Saskatchewan, there almost always is at least one piece in Value Village. In the Mennonite Clothes Closets it's rarer, and same with the Salvation Army's. I've seen a few abused pieces that made me very very sad. There are usually lots of Termo-Rey and the other glass companies as well.
Some eye candy for you!
Also does anyone know of an online English Pyrex reference site? The one I have linked to on my blog doesn't work anymore. :(