I am not sure. In my experience on my server, competition is so fierce that the mats cost more than the finished item. Just looked for example and:
So there is some cash to be made out of cinderbloom-->ashen pigments maybe, depending how many you can flog, plus it takes time to mill. I just did mill 235 cinderblooms, ended up with 116 ashen pigments and 8 burning embers.
Pigments have a weird price, they rarely have a reliable supply and sell rate compared to the ink or herbs. On your server ashen pigments sold for 10-12g each, with a max price of 24g and a bottom price of 4g. So while it can be better to sell the pigment once in a while, it's not where you'll be able to unload the product of milling 8000 herbs.
Where you will be able to use ink by the inventoryfull, is on glyphs and Mysterious Cards. So what I do is I use the price of those as my baseline, and value everything else from that. On your server I might use these prices:
10g per mysterious card (sales in the last day were between 9.8g and 10.8g)
30g per glyph (since I need 1 ink for 1 card, and 3 inks per glyph, any glyph)
10g per burning embers (15g inks, sometimes up to 40g per pigment on actual sales)
So I value one ashen pigment at 5g, and one burning embers at 10g.
Low end Cata herbs mill into 2.5 ashen and 0.25 burning, high end cata mill into 3.0 ashen and 0.5 burning on average. Your personal results from the low end cinderbloom was 2.47 ashen and 0.17 burning, which was a bit unlucky.
That means with the prices I have set as my minimum prices (I will be able to sell both types of ink and pigments at higher prices at times, but that's not where I'll be able to reliably use 2000 ink per week), these are the milling values:
High herbs: 3 * 5g + 0.5 * 10g -> 20g per mill -> 4g herbs, 80g stacks
Low herbs: 2.5 * 5g + 0.25 * 10g -> 15g per mill -> 3g herbs, 60g stacks
So with the prices above, I could buy around 4000 whiptail from AH right now, mill it, and get around 100% profit on the gold spent, even without going for the higher value auctions that sell more slowly.
If you can, try to sell as much Blackfallow (or any kind of lower ink) you can for more than 10g each. Try to sell Burning pigment and inferno ink for as much as possible. But use the prices for the cards as what you base your profit off of, and anything you get above that is a bonus. And with the card value as the base, you can easily get a lot of profit by milling.
And yes, it takes time to mill, that's why you can get 100%+ profit from it. If it was as easy as smelting, it'd drop down to the point where it would actually be difficult to spot a deal, not how easy it is now. If we say that you bought 4000 whiptail at 40g per stack, ended up getting the 100% profit I used as minimum value of inks, and used 10 seconds per mill total (buying herbs, milling, making ink, making cards, selling on AH), then you'd get 3600g profit per hour from it.
Get TradeSkillMaster, use the Destroying addon to it. There you can go into the milling option, set a 5g value for Blackfallow ink, and it will search for all herbs you can mill for that end price and prompt you to buy them. If you're making glyphs you'll need all inks, so do that 5g for every ink and buy it out. I recently turned 100g into 40000g in 3 weeks on a level 20 char with 225 inscription, because I took control over the lower herb/ink/pigment market and sold minor glyphs as well.