So, you're ready to make Organic Cheetos and Spherified DRY Lavender Soda Bellinis, but you can't seem to find sodium alginate and calcium chloride at the neighborhood market. Don't worry - you're not alone. Luckily, there are a number of online suppliers who can easily fill the "Modernist" shelf of your spice rack. Here are a few of the better sites for finding tools and ingredients for your foray into future food.
http://www.lepicerie.com - a huge collection of spices, flavorings, additives and tools. Sold in small and large quantities.
http://chefrubber.com/ - targeted at pastry chefs, they carry a wide variety of molds and confectionary tools, as well as serving pieces and and decorating supplies.
http://www.le-sanctuaire.com/ - a full line of molecular gastronomy chemicals, as well as a very impressive collection of tableware and specialty foods.
http://www.dcduby.com/ - For our Canadian friends, they carry a relatively complete selection of molecular gastronomy ingredients.
http://www.tienda.com/ - Carries the complete line of Texturas products. This is the brand created by Ferran Adriá, and offers accompanying recipes for use. Although convenient, you pay a premium for the brand name.
WillPowder (via Amazon.com) - Great prices on large quantities (1 lb.) of common molecular gastronomy chemicals. Next-day delivery available through Amazon.