I am always finding gear that I would rather sell for gold than destroy. Is there anywhere within Hogwarts that you can go to sell unwanted pieces of gear?
I am not sure, I havn’t come across one but since you can easily fast travel to Hogsmeade, it doesn’t make that much of a difference, does it? You will likely have to fast travel to the vendor regardless of its location in the game, be it the castle or Hogsmeade. Shouldn’t cost you any more or less time to fast travel to Hogsmeade instead of somewhere else within the castle.