The only time I've ever seen it in a catalog was at Nasco. They sell arts & craft supplies to schools. The sta flo starch is used as a fix in various crafts. I'm pretty sure they ship to canada. Only problem is that the starch is liquid, so heavy. here's a link, you can send them an email and see. They are in Wisconsin, so that's sort of close to Ont.
http://www.enasco.com/Search?q=starch&x=9&y=11