Moving elegantly from the discussion of dying to the discussion of dyeing, this post is in reply to an e-mail from Syrien, who wrote "The thing that has intrigued me which I was hoping to hear your reflections on is the dye prices. What makes a color popular? Some could surely be attributed to showing off that you can afford the best (dressing all in black). On the other hand, gold dyes had a boost of popularity in my ah: At one point I discovered I could sell a gold dye for 200-300s, while the yarrow roots needed to make them were in the auction house for 2-3 silvers a piece. I kept posting the gold dyes for higher prices (only one in the AH at a time to try support a notion that they were rare), and at most sold one for around 500 silver before the market collapsed. Currently the gold dyes sells for 80 silver on a lucky day. The yarrow root prices reflect the gold dye prices. Olive dyes are currently more in demand (for the same price) than umber dyes. I've also wondered if the names of the dyes matter (would dark blue be a more beneficial name for a dye than navy because people would search for blue if they had that color in mind?) Is violet dye too 'girly'? Are some colors seen as appropriate for some classes (minstrels can wear bright colors, hunters should wear olive?)". Sorry for the late reply, I've been busy walking on sunny beaches. Keep sending those mails with ideas of what you'd like to have discussed on this blog.
I wouldn't read too much into the dye prices on the Lord of the Rings Online auction houses, they don't seem to be really settled yet and fluctuate wildly. One problem is resources like yarrow roots. These spawn randomly all over the world, but sparsely, and are rather rare. If you wanted to go out and collect a large amount of yarrow roots yourself, it would take you forever. You have to rely on the kind of people who pick up everything clickable they see and sell it on the auction house to get a supply, and that sort of supply isn't very reliable.
The most reliable dye is olive, because it uses copper salts, which are found when mining copper. As there are lots of people mining copper, and the chance to find salts isn't that low, there is usually a good supply of the resource around. If you have several alts, and one is a prospector you can gather the salts yourself, and make a tidy sum on the side from all the copper you collect in the process.
Similar thoughts apply to other colors, so you sort them into the two categories of dyes needing plants like gold or navy, and dyes needing metal salts, like olive and umber. The only exception is violet dye, which needs juicy blackberries, which can be grown with master farming. As farming is now relatively cheap, getting hold of those shouldn't be too difficult.
Of course that is only the supply side. Demand of dyes is a more complicated question. Many colors in LotRO are rather subdued, to fit in with graphical style. You can't really dye your armor in clashing neon colors. Especially the lower level dyes are all very much natural tones, yellows, browns, and olive green. Not many people want to pay lots of silver to color their armor brown. The olive dye seems to have a steady demand. Not sure about the higher level, more primary color dyes, but I'd guess clearer tones are more in demand, as they are more visible. Why spend money on dyeing your armor if nobody even notices it? A related issue is that dyes aren't applied to the whole surface of the item you use it on. If you have a metal helmet or chainmail shirt, you might find that they majority of the surface keeps its original metal color, and the dye is only visible on the borders or embroidery.
Dyeing armor is only for show, and the demand thus left to individual preference. Thus with the supply being low and the demand unsteady, prices will probably always fluctuate. One guy wanting to color his whole armor the same color can easily use up all the available dyes on the auction house. Trying to get a guild to wear guild colors could completely overwhelm the dye market. But then you'll have long spells where nobody buys any dyes. I wouldn't consider dyes a reliable source of income for a scholar. I made lots of olive dyes with my scholar, but only because I had the salts from copper mining, and making the dyes was an easier way to skill up scholar than finding ancient texts.