I can confirm this. Without these components you cannot dye fine plate.
There used to be only two merchants who sold the jar of acid and and empty vials, Grham Embersmith in High Keep and Ukla in Rathe Mountains. As of now they only sell part of the items needed and the book on how to dye and stain.
Source:
http://web.archive.org/web/200010111...high_keep.html
http://web.archive.org/web/200010120...rathe_mts.html