Probably the most intensive site on the Net about the art/science/subject of dyeing, no matter what material you're working with. Ph. D., Paula Burch's All About Hand Dyeing website.
Plan to spend some time reading through this site because the site navigation is somewhat complex and there is a LOT of information and detail. Plus FAQ’s and an archived Q&A.
[TIP: From several instances of personal experience within this site]
To save yourself a great deal of future search time later, when you come upon a helpful subject topic, "bookmark" or "favorite" it in your browser.
There's also (worldwide) links to reasonably priced suppliers of the materials mentioned within the site. Despite living in PA (and having East Coast alternatives), I ordered from Dharma Trading Company in CA and was very pleased with cost, shipping and delivery time of UPS Ground [right after Xmas no less!].
The time it'll take to find what you're looking for will depend on what fiber you're working with.
Of interest to the wool & Kool-Aid dyeing crowd and anyone who wants an overview on protein fiber dyes. Plus link to links within the site for more information:
Quick and dirty, general dye-type overview and links to specific site pages:
Main Site Link: