I think he has like a code for it. Like a card code. And then you use that code to get like in game mail that includes this item. That might make sense.
Or else maybe he sells you the account with the item bound for 70k. which is then a really good deal.
Or maybe he finds out where you live, and sneaks the collector card into a pair of your shoes but steals your laces. He never informs you that the card is there and you're so distracted by the laceless shoes that you forget about the Flag of Ownership.