Long Lost Art of Swapping

I'm going to talk today about something that seems to have been completely forgotten about by a large number of players. Today we're gonna discuss essence swapping. In WoTLK I can't even begin to tell you how much gold I made by essence swapping. If you read the flavor text of any enchanting essence (ie. Greater Celestial Essence) you will see that they can turn into smaller, or greater essences depending on which state they are currently in. Greater Celestial Essence will swap into 3 Lesser Celestial Essence, and vice versa. So what's the big deal? The big deal is that many many times, one of the two types of essences is severely under priced.
On my server right now, Lesser Celestial Essence is selling for 10g each, while Greater Celestial Essence is selling for 39g each. Quick math shows that 3 Lesser Celestial Essence at 10g each is 30g, giving you a 9g profit per swap to Greater Celestial Essence. Usually there are fewer of the Lesser Essences on the AH but that doesn't mean you shouldn't take full advantage and profit while you can. This swap can also work in reverse. A quick look at another realm on the Undermine Journal shows that the Greater Essences are selling for 30g while the Lesser are selling for 15g each. Swapping down in that case nets you 15g profit if they all sell, and trust me, they do sell. You don't just have to use Celestial Essences though, as this does work with any of the enchanting Essences. Take a quick look at your AH and see if there's not some free gold laying around waiting on you to scoop it up.