Sometimes it’s really not easy to get all white recipes if you’re not willing to pay insane amounts of gold for them in the auction house, most of the time when you show up at a vendor it already has been bought for that very purpose – to resell it for lots of gold. The Felcloth Pants in Moonglade, the Admiral’s Hat in Stranglethorn and others are the ones for me as a tailor, but it counts for pretty much every limited item you can get from vendors. Someone will show up, eventually even camp the NPC for more, to make gold from the limitation.
Quite annoying, but what can we do about that? Nothing. The best thing to do is to park an inactive alt next to the vendor and check occasionally, preferably at times where most people are working or sleeping. Sooner or later it will be in stock! o_o
And once you get the desired item, you can buy even more – to resell them for gold..^^