You can get this enchant from most (If not all) enchanting      suppliers in the main cities, (Orgimmar, Thunder Bluff, Undercity, Silvermoon City, Stormwind, Ironforge, Darnassus, and The Exodar) (I do not think Shatt/Thallmar have this. However there is only a supply of 1 and there is a cooldown, not expensive ethier.