Wendy Welch, The Little Bookstore of Big Stone Gap
Welch is specifically talking about books. As the owner of a small used bookstore, she recognizes that persons thinking of selling books to create more space in their homes may find it difficult to part with certain books because of the memories attached to them, while customers seeking to replace books they loved in their youth may be willing to pay more than the books are actually worth.
Most of us who have books have at least some of them chiefly because of the memories attached them. They may be worthless in the marketplace, and we may never want to read them again. Yet they are priceless to us, or at least those "moments of memory" are priceless.
I still have a vocabulary book I spent hours with as a child. It shows pictures of ordinary objects with the appropriate word under each. I don't know whether my lifelong interest in words stemmed from that book or whether my interest in that book stemmed from some innate love for words. In any case, that is one of my priceless books.
Another is The Merry Adventures of Robin Hood by Howard Pyle, illustrated by Lawrence Beall Smith. How I loved that book. Today I can't see it on the shelf without sweet memories being triggered.
Look through your own library. You will likely find books that have great value to you and books you might sell for a good price. Chances are they will not be the same books.