Definitely check out GNC, Loblaws, and the Nutrional Houses.

I've been to one of the Nutrional Houses myself (the one in the Eaton Centre) and their prices are very very good.

I've bought iron supplements and the occasional Protein Revolution bars and have always been impressed with the prices.

You'd been surprised where you can find low-carb stuff, although it's not necessarily called low-carb.

I found sugar free vanilla syrup at the Timothy's chain of coffee places. $11.99 (no tax) for a bottle. And it's yummy!

Chris