I'd order from Pampered Chef over Zellers or elswhere. I haven't used them, but I have a feeling the generic stones be nearly as nice in quality as the Pampered Chef stones. My family has been using Pampered Chef stones for 5+ years now(the same ones for that long) and we've had no problems with them. They've replaced almost all our bakeware(except cake/muffin pans). I think they may even have a warranty.
Pampered Chef stones =

Worth the extra $$ and the time to get them.