How to get Tabard of the Lightbringer? Any place to buy Tabard of the Lightbringer?

You get this quest from
http://www.wowhead.com/?quest=24914

When you kill the Lich King with a player wearing Shadowmourne in the raid, you will get an additional item - Unsealed Chest. After bringing the chest to Darion he will open it up and let you bring the items back to their respective owners to get your rewards :
Tabard of the Lightbringer- A tabard with a very shiny on-use effect.

Reins of the Crimson Deathcharger - A brand new mount that looks like the Death Knight’s class mount.
Muradin’s Favor - A 10-minute Frost Dwarf transformation.
Jaina’s Locket - A portal to Dalaran on a 1-hour cooldown, you finally have your own pocket mage!

Sylvanas’ Music Box - A music box that plays Lament of the Highborne.

BTW, IF YOU WANT TO BUY ONE, YOU CAN TRY THIS ONE: GUY4GAME.COM.

Uther the Lightbringer says: Arthas…
Uther the Lightbringer says: Alas, hero of Azeroth, you give me a greater gift than you know.
Uther the Lightbringer says: Long have I struggled to forgive the prince for his terrible transgressions.
Uther the Lightbringer says: My soul has been wracked with unbearable anxiety, dark thoughts… distancing me from the Light.
Uther the Lightbringer says: I recall clearly the gleam of pride in his eye as he stood before me, eager to defeat the enemies of the Light…
Uther the Lightbringer says: Eager to defend his people, no matter the cost.
Uther the Lightbringer says: It is this memory of Arthas that I choose to keep in my heart.
Uther the Lightbringer says: I shall always be in your debt, friend.
Uther the Lightbringer says: Thank you.