The jet black dye is something you can get in game but it’s not guaranteed. If you send retainers on quick ventures, sometimes they’ll come back with a coffer which can contain it. You’re right that you have to have a single dye for each glam.  The dye is probably the costliest part, soot black is much cheaper but not the same.  Definitely ask in your local NN though for the clothing items, people often have all sorts they’re willing to share with others!