Just found another great benefit of being an engineer. Engineers have the easiest time controlling the Frozen Orb > Eternal Echange Market. Frozo the Orb Exchanger is located right outside the Dalaran Engineering Building, which houses the Engineer Only Auction House Access in Dalaran. Also close by are the Anvil/Forge, Mailbox, and the Heavy Borean Leather to Arctic Fur Exchanger. The close proximity of both the Exchangers and the Auction House, make this an easy spot to search for Orbs then convert them into the more higher prices Eternal flavor of the night. This can also be done swapping heavy borean leathers as well.
So you do a search and see that Frozen Orbs are at 22g, and Eternal Life is at 36g and Eternal Fire is at 38g. What do you do?