Legion's transmog changes allow you to 'learn' the look of an item adding it to an appearance collection for your account, to add the item it must be soulbound so that you can't trade it around to others. This change means that all white shirts are becoming green quality and bind on equip items.Some shirts were made unobtainable years ago back at the end of Wrath and have increased quite a lot in value and have been further increasing since this transmog change was announced and prices can go over 50,000 gold on some of them!If you leave the shirt equipped on your character when patch 7.0 launches the shirt will automatically bind to your character meaning you can't resell it even if you have duplicates on other characters equipped. Proof here on my alt, shirt equipped on live and shirt soulbound after transferring to the 7.0 PTR.Here is a list of shirts that have some value and are rarer that you should unequip if you'd like to resell or have duplicates of:Pre-Cata Starting Shirts, double check ID's of the items as there are some that have the same name as cheap obtainable shirts.Lookout's TunicFootpad's ShirtTrapper's ShirtRugged Trapper's ShirtPrimitive MantleThug ShirtSquire's ShirtRecruit's ShirtBrawler's HarnessPrimitive Mantle Note this shirt was missed by Blizzard and they forgot to change it to BoE on PTR/Beta so report it if you can.Trapper's ShirtWarder's ShirtScout's ShirtRecruit's ShirtSquire's ShirtInitiate's ShirtRare drop recipes that craft shirts.Pattern: Rich Purple Silk ShirtPattern: Red Lumberjack ShirtPattern: Blue Lumberjack ShirtPattern: Green Lumberjack ShirtPattern: Red Workman's ShirtPattern: Blue Workman's ShirtPattern: Rustic Workman's ShirtThese shirts are rare drops.Deckhand's ShirtSleeveless T-ShirtRed Shirt - While VERY rare, this shirt is the exact same model and color of a cheap crafted shirt. This would only be desired by collectors who want to have the red shirt of the red shirt guy.Also good ideas for investing as they will likely go up further in the first month or so of 7.0 and Legion as demand increases and supply goes down. Here is a TradeskillMaster group if you'd like to search for these shirts.