Where do I buy food additives (not in bulk)? I occasionally want a pure food additive for various reasons (pure potassium chloride for sports drinks, pure MSG for everything), but I can't find any decent places to get them except amazon.com. Now I'm looking for disodium inosinate, and even Amazon doesn't have that. I expect I'll be looking for weird things like this in the future, so I'm wondering where people buy food additives (besides bulk suppliers).
Hey guys, since the question was posted they opened up Modernist Pantry, which specifically caters to this need. They supply chemicals for molecular gastronomy in consumer-sized portions.  

For $10 or less apiece, you can order small amounts of emulsifiers, gelling agents, foaming agents, etc. They also have spherification kits, the Texturas products, and Molecule-R's lineup.