Always interested to hear what people have in their collections. The only rule is it has got to be tradeable, even if it's since been made unavailable.
For me it's probably a pair of
Glacial Gloves, a
Rugged Trapper's Shirt, or
Plans: Masterwork Stormhammer.
- The Glacial Gloves require two things from Naxx 40 man, 5 Frozen Runes and the craft itself. WoWhead says 2.53 mil
- The Rugged Trapper's shirt was the starter shirt for Night Elf and Dwarf hunters only. It was changed to Rugged Trapper's Vest in Patch 4.0.3 (Catacylsm). WoWhead says 2.07 mil
- The Plans: Masterwork Stormhammer only dropped from Goraluk Anvilcrack in the original Upper Blackrock Spire. When that boss was removed in Patch 6.0.2 (Warlords), so were the plans. WoWhead says 1.55 mil
No clue if those WoWhead prices are real or not, but it's at least something to refer too. If there's a more accurate pricing elsewhere, please do say so.
What've you got?