Where exactly can I find "nigari" in Toronto?

Nigari is a coagulant used in the tofu making process and contains/is magnesium chloride. I have looked everywhere that was suggested to me, still no luck. Even stores that make it have not helped. I know I can order it online, but I want to source it locally. No generic answers please! i.e. look in a Japanese grocery store. Been there; done that.