I guess you all know the instance scholomance and don't see it as a good farm spot but i sure do. I clear the first room on my mage to get
Formula: Enchant Weapon - Lifestealing
It sells for around 75-100g on my server
It's dropped by Spectral Researcher - NPCs - WOWDB and got 5,74% droprate.
After grinding there about 45 minutes doing 5 resets i ended up with 3 Recipes and vendor crap for 60g! and I don't even know how many gold i got picking up coins.
Then i got the idea.. If you would like to grind there alot it would be better with a shop nearby. Then i remembered
Spectral Essence
It makes you see ghost outside of Scholomance and there is a blacksmith out there!
You get it from this quest chain:
Doctor Theolen Krastinov, the Butcher - Quests - World of Warcraft
Krastinov's Bag of Horrors - Quests - WOWDB
Kirtonos the Herald - Quests - WOWDB
Happy farming