Wikia

A shirt is a wearable item that has its own dedicated slot and does not have any functional purpose besides decorative appeal or bragging rights.

Source

Tailors can make a variety of shirts, but they can also be purchased from vendors, found as drops, or even received as quest rewards.
The [Sleeveless T-Shirt] is the only shirt obtained through PvP.

[Sleeveless T-Shirt] - Very low drop rate on Alliance corpses in Alterac Valley. The only shirt obtained through PvP. "On the collar it reads, 'Inspected by Earl Z. Moade.'"

[Deckhand's Shirt] - Dropped by Southsea Freebooters in the Barrens
[White Tuxedo Shirt] - Found in Easter Eggs during Noblegarden.
[Martin Fury] - This is a Game Master shirt.
[Shirt of the Future Champion] - This is a PTR shirt for testing Hard Mode Ulduar.
[Shirt of the Yogg-Slayer] - This is a PTR shirt for testing 25-man Ulduar.
[Shirt of Titanic Scaling] - This is a PTR shirt for testing 10-man Ulduar.
[Shirt of Uber] - This is a PTR shirt for testing heroic Argent Tournament raids.

Following shirts are sold by Lisbeth Schneider in Stormwind City.

Following shirts are sold by Karandonna <Clothier> in Dalaran.

Following shirts are sold by Angelique Butler <First Aid Supplies> in Dalaran.

Following shirts are sold by Broxel Goldgrasp <Souvenirs> at the Argent Tournament Grounds and have faction requirements.

A few shirts have personal value as parts of interesting sets of clothing, or as proof of obtaining a rare drop or rare quest, but most are considered junk to non-roleplayers.
Most shirts do not bind at all and may be purchased from vendors, other players, or the Auction House. There are seven Bind on Pickup (BOP) shirts that are available to both factions but one is only conjured during a boss fight.
No rare shirts exist.
The [Precious's Ribbon] is the only uncommon quality shirt that exists in the game. It is also the only available shirt to feature an equip action that puts a buff on the character. The buff reads "Best in Show".
- Mists of Pandaria may include more uncommon quality shirts for guilds, if the Beta is any indication.^[1]
The [Epic Purple Shirt] (a TCG loot card redemption) is the only epic quality shirt that exists in the game (excluding PTR shirts). It is also the only shirt to feature an on use action besides the conjured shirt in Icecrown Citadel (10/25) and the Game Master shirt.
The [Martin Fury] was the only artifact quality shirt that exists in the game. It was a Game Master shirt and players only got it by mistake. If you ever got this, you needed to report it to a game master or you would get permanently banned like Karatechop from Vek'nilash US. At some point it became a poor item.
The [Master Builder's Shirt] has the highest item level of all available shirts available to players (excluding PTR shirts).

^ uncommon Shirts - Added in expansion: Mists of Pandaria. Wowhead. Retrieved on 2012-05-25.

Wowhead Shirts

Wowhead News Best in Show: A Guide to All Shirts by perculia 2012/02/25 at 10:01 AM