Perhaps you will be interested
The tusks drop from Garrosh after the final battle of the Siege of Orgrimmar. They are epic-quality DPS plate shoulders. It also can be listed on the Black Market Auction House.
Here you can buy Tusks of Mannoroth for EU or US Servers.
Also you'll get guide for receiving Tusks of Mannoroth
After patch 10.2 might will need character transfer for access to BMAH