This was initially exclusive to the gold guide but I'm copying it over here for further discussion.
Blacksmithing is a profession that offers several profitable old world crafts. In fact, this is one of the greatest perks the profession offers. This niche market is one seldom tapped by goblins.
For the better part, these profitable crafts are for the purpose of transmog. One particular group of items, the “Reborn”, were introduced in MoP and require , which are still on daily cooldown. This means you can stack Blacksmiths and still reap some daily benefits from cooldowns – just like alchemists!
Learning the Lightning Steel Ingot recipe requires a bit of work. First, head over to Isle of Thunder. Work your way to Itoka and serve him a can of whoop-ass. Any character 93+ should have no issue soloing him.
Itoka drops quest item, which starts a quest. The turn in is nearby and has no requirements, just run over to the forge and turn in the quest. As a reward, you will learn how to make the Ingots and receive the recipes for all rare-quality items below.
Upon crafting the lowest level item, you will learn the next item in the chain. For example, crafting Fireguard teaches , which in turn teaches . These items can't be crafted at regular forges either - you'll need to head off to the thunder forge, which is a pain in itself.
Obviously, there are many more crafted transmogrification items you can sell. I’ve identified a list of ~200 crafted blacksmithing items that are high potential candidates, and just happen to run my own profitable transmog business as well.
NOTE: I highly recommend running this business on a separate profile, as to not interfere with your other gold-making operations.
You can import the full list and structure with the following import string:
I’ve broken down items by slot since you might want to cut some groups out completely (usually starting with wrist, gloves, waist, etc).
The list isn’t foolproof. I started with a huge list of crafted items worth 300g or more, and whittled the list down to items with potential. I’ve had experience selling at least 50% of the items on the list, so it should be a solid list as a whole.
To queue up items intelligently, use DBGlobalHistorical for valuing items and their crafting materials. Under Crafting -> Options, put DBGlobalHistorical as your default material cost and default craft value method. Remember, a lot of these transmog items are rare, so we need to take a broad look at their value to see what’s worth crafting.
Where your crafting operation is concerned, look to make hefty profits on each craft. Something like max(10% crafting, 100g).
And that's it! Nothing too fancy really.