Where are the best places to source ingredients?

The dreaded "big-box" Wal-Mart fills most of my needs, from Vital Wheat Gluten, to graham, soy, and rice flours to add to my breads. Sam's Club fits the bill for Instant Yeast at a great price, and Whole Foods carries some of the exotica that I occasionally use, like Pearl sugar. E-Bay is my source for baking pans, generally, as I use cast iron. ~Kizzle