I've noticed what appears to be a monetary correlation between Exquisite Essence and Fiery Brimstone, which could mean it is possible to make money crafting by manipulating exchange rates. I assume the correlation is because folks that have high level Blacksmithing plans can directly convert Exquisite Essence to Fiery Brimstone via salvaging. I'd like to get in on that action, but I'd prefer to buy the most efficient Blacksmithing recipe off the AH, as I'll presumably never see one drop. If I'm focusing just on minimum crafting materials (and assume I'm buying them off the AH), then which recipe or recipes is the best choice?
Short Answer: This is not economically feasible. Even with the cheapest recipe, you have, at most, a 0.3% chance to break even.
Attempting to convert Exquisite Essences into Fiery Brimstones consists of the following steps:
To this end, it makes sense to find a recipe that requires the least amount of Exquisite Essences. I have found the Exalted Sovereign Vambraces, which take 14 Exquisite Essences. At current Market Prices, the total crafting cost is:
This will net you a 0.1% chance to salvage it into a Fiery Brimstone. At current Brimstone costs of 165,000, you would need to salvage Brimstones at 1 every 3 crafts just to break even. At three crafts, you have an absolute maximum of a 0.3% chance of garnering a Brimstone, which is not a very good chance at all.
Looking at any Legendary or Set crafting recipe shows that each one of these requires two Brimstones to craft, and will only salvage into one, resulting in a net loss.
A much better way to try to break into the Brimstone market is to buy as many rare Inferno-class pieces of gear you can as cheaply as you can, and salvage those for a chance at a Brimstone.
I'm not completely sure that I understand your question - but are you referring to crafting level 60 rares, and then salvaging them for a chance at brimstone?
So its clearly not worth it with the current prices at around 150k gold.
Note that only lvl 60 rares have a chance to salvage into brimstone. The cheapest ones are Glorious Doom Armor and Glorious Hellscape Mask, you get both simply by leveling up the blacksmith so there is no need to purchase any recipes.