Hello.
First of all, I'd like to say that I have searched the forums here, and I didn't find anything similar to this. But if it's a repost, I'm extremely sorry.
As you all know, you can buy stuff in Dalaran with Frozen orb, but what we're aiming for here is eternal fire. Eternal Fire goes for about 25g on AH on my server, and Frozen orbs go for like 5 gold, making it a 20g profit, just for buying Frozen Orbs, going to Dalaran to buy Eternal Fire and then sell it on the AH.