Trinket
Mirror of Broken Images
Source: Requires Exalted with Baradin's Wardens (Alliance) or Hellscream's Reach (Horde)

Trinket
Lifebound Alchemist Stone
Source: Crafted through Alchemy (Alchemist-only item)

Alternative: Leaden Despair (Drops from High Priestess Azil in The Stonecore Heroic)

Weapon
Zin'rokh, Destroyer of Worlds
Source: Acquired through WoW Cataclysm Classic Gold Archaeology
Alternative: Sword of the Bottomless Pit (Drops from Ozruk in The Stonecore Heroic), Whitefin Axe (Drops from Ozumat in Throne of the Tides Heroic)

Relic
Notched Jawbone
Source: Crafted through Inscription
Alternative: Stalagmite Dragon (Drops from Slabhide in The Stonecore Heroic)

BIS Gear for Frost and Unholy Death Knights (Pre-Raid)
Frost and Unholy Death Knights are powerful DPS classes in raids. Frost Death Knights provide the Improved Icy Talons buff, while Unholy Death Knights offer consistent melee damage. 
Below is the pre-raid BIS gear for cheap WoW Cataclysm Classic Gold these specs, with some items overlapping with Blood DKs.

Head
Reinforced Bio-Optic Killshades
Source: Crafted through Engineering (Engineer-only item)
Alternative: Helm of Setesh (Drops from Setesh in Halls of Origination Heroic)