I\m not gonna waste your time, so lets get into it.

What you want to Obliterate:
Infernal Alchemist Stone - Item - World of Warcraft

When should i buy it?
If its lower than 130% of the obliterum price, buy it!

Obliterum is 3.1k gold each on my server, and the alchemist stone was 3.1k-3.9k
gold before i bought 47 of them, now its around 4k so im waiting for it to numb down.

Why should i even do this?
Because you'll recieve 132-179 obliterum ash each.

Easiest gold flip of my life.