This merchant sells packs and armor collected from adventurers who did not make it out of The Dungeon of the Mad Mage. The Collector has a hired Dragonborn mercenary who delves into the dungeon to collect the packs and armor to be sold. All packs remain unopened, so The Collector has no information regarding what is or is not in the packs.
All items are from Wizards of the Coast: Dungeons and Dragons 5e, various books.