Michaels does sell the bigger hooks most smaller yarn shops in Canada have to order them in. I did also find a couple of the bigger ones at fabricland also. Depends really in what province you are in and the demand. What size are you looking for? q hook perhaps?
I often use crochet hooks from 8 to 15 for my t-shirt yarn bags and baskets. I buy them in a shop very close to my house. I think you should find them in shops where they sell yarns and needles