I’ll be adding more here but in the meantime, here’s a list of suppliers for dry pigments. There are thousands of pigments, some safe and suitable and others not. Please consult with me before placing an order. Your health, the longevity of your artwork, and keeping you from spending too much money – all these things are important and I’m glad to help you find what you need.
Generally speaking though, iron oxides are the cheapest, safest, most readily available pigments. They’re dirt cheap, often being actual dirt or crushed rocks. You can in fact make these pigments from certain rocks if you like. Iron oxide yellows and reds are available inexpensively from ceramics suppliers such as MidSouth in Nashville. A pound of Iron Oxide Red is less than $5, for example.
Pigments are generally sold by weight, not volume. Some pigments are naturally heavier than others. Also, tinting strength varies and you’ll be getting the pure pigment, without any fillers or extenders. This is different from pre-made oil paint, for example, where you buy by volume and the tinting strength has been adjusted for very intense colors to make it manageable.
- Jerry’s Artarama, Knoxville
Difficult to find, higher saturation artist pigments - NaturalPigments
Large selection of specialty pigments - Kremer
Every pigment under the sun - EarthPigments.com
Mostly earth colors - Guerra Paint
Difficult to find, higher saturation artist pigments - MidSouth Ceramics (also look under Chemicals or Search)
Iron Oxides, red and yellow
Chromium Oxide Green
Titanium Dioxide White
Whiting for making gesso
Rome 
Cookeville 
London