Scarlet Crusade Hidden Transmog
The Scarlet Crusade Hidden Transmog can be purchased from the Scarlet Quartermaster, an NPC found on the Darkmoon Island during the Darkmoon Faire World Event.
/way Darkmoon Faire 58 80.6
At first glance the https://www.wowhead.com/npc=108785 raises some questions about her intentions. However, if you interact with her while wearing the https://www.wowhead.com/item=23192, she will offer you the option to purchase transmog items.
- Everyone can purchase https://www.wowhead.com/item=138429 for 25,000 gold.
- Hunters and Shamans can purchase https://www.wowhead.com/item=138430 for 10,000 gold.
- Warriors, Paladins and Death Knights can purchase https://www.wowhead.com/item=138431 for 10,000 gold.
Tabard of the Scarlet Crusade
https://www.wowhead.com/item=23192 drops from Armsmaster Harlan in Scarlet Halls. The drop rate seems to be around 1%, however you can farm this on normal again and again until it drops.
Note: You don't have to wait for the Darkmoon Faire World Event to be active, you can farm this item whenever you want.