Schematic: Hard Khorium Goggles

Source
Any mob in the Sunwell Plateau has a chance to drop this, droprate is estimated around 0.02%. These goggles are even better than Tier 6 headpiece, thus making the schematic sell for very high prices in AH in it's time. As of Wrath of the Lich King and upcoming Cataclysm the price has gone down tremendously, but the rarity still makes it worth some gold even as an outdate gear piece.