Any old stuff? 1920’s or earlier. Thats where the more valuable ones are. Most of those from 40’s on can still be bought at face value or less. So many people stashed sheets of them and they keep coming out on the market. If you are collecting, they are still good clean copies, but otherwise they are postage. For those 3 and 4s, It probably cost me more to mount them on pages than they they are worth.