What I do is to give them a business card and tell them to put the card with the chips or whatever and if they decide to sell to call me. I got a call Saturday from a guy who wants to sell some silver coins from a card I left at a 50 mile long yard sale last fall. Ya just never know when it will pay off. I once bought 800 silver strikes from a relative of a guy who died 5 years after I gave him a card.