Protein Powders:
I buy my Isopure Protein Powder online at ca.bodybuilding.com. Cheapest I can find online so far (including shipping). The deliver to Canada (i think they have a local warehouse), and I've not had to pay any duty.
I get the Dutch Chocolate (for drinking) and the Unflavoured (for cooking or sprinkling, lol) kinds. Both are lactose free, gluten free. The Dutch Chocolate per scoop is: 110 calories, 25g of protein, >1g net carbs, >1g of fat. The Unflavoured is the same except zero fat and carbs.
*Note: I just hate all sweet things now, and the Dutch Chocolate is the least sweet of all the powders I have tried. It's not for everyone, especially if you have a sweet tooth.
https://ca.bodybuilding.com/store/isopure/zero-carb.html?skuId=NB015
Vitamins:
Cheapest is at No Frills, or Costco when on sale. Costco is also the cheapest for Benefibre.
Sugar Free popsicles and stuff:
I've no input on this as I've never had any...the whole disliking sweet stuff saved me from this part.