I wanted to share some of my favorite sources for hard to come by items. FYI, you should always check your LYS first! Some things just can't be had locally, and they can be hard to source, especially specialty Dyes, fiber, mordants & paints.
Botanical Colors: My absolute favorite place to order any natural dyestuff. Botanical Colors only sells the highest quality dyestuff and Kathy (the owner) is an incredible source of knowledge, kindness and generosity. Botanical Colors' natural dye kit is a great way to get a variety of dyes and directions for the beginner. I am looking forward to her future class offerings so I can finally visit Seattle and dye dye dye. If I can get it from Kathy I don't even bother sourcing it somewhere else, 'nuff said!
Dharma Trading Company is truly a cornucopia of fiber arts. They carry every single item, ever--well, almost. If you need yarn, fabric, paint, tools or clothing blanks for dyeing this is your spot. They have loads of tutorials, FAQs that answer most questions & incredibly, real people answer the phone and they are all fiber folk so they can help you with most questions. My only caveat is "Be Careful" you can definitely impulse purchase!
Kremer Pigments Inc. They basically have the craziest and most amazing array of painting supplies in the U.S.A. If you are interested in an obscure & historical mineral, pigment, dye, glue or balsam this is the place. Kremer is where conservators and art restorers shop. It's an amazing place and if you ever have the chance to visit, you oughtta.