My day job is in a different industry. We win alot of awards for the products we produce. Until recently we have always kept the ribbon and plaques when the product was sold at a Charity Auction. In the past several years, there has been a shift and that is the person who buys the product expects to keep the ribbon, plaque, silver cup etc. Even though the money goes to charity they figure that they paid the money it belongs to them. Long story short, I would make sure that everyone is on the same page before the transaction is final.