Initiate's shirt is an item that was no longer available since cataclysm. Transmoggable in Legion
selling for 250k gold
it's on Shattered halls. You can pay for the character transfer to your server if that's something you'd be interested in.
otherwise on Shattered Halls will be the trade.
shirt can be seen here: Initiate's Shirt - Item - World of Warcraft
inbox me offers, or concerns.