I was at a (non-audiophile) friend's new house that he just moved into. During the move, he found stashed away in a far dark corner of his old house, a stash of 78 RPM records that had belonged to his grandmother...including Fats Domino "Blueberry Hill"; Les Paul and Mary Ford; The Platters; Bobby Darin, etc. They all looked in excellent shape and had been kept in sturdy record "book" made specifcally for 78s, in which each 78 slid into a sleeve with a hole so you could read the label.
I was impressed, so I offered to take them off his hands. He declined. So I just told him to store them upright in a dry, cool, dark place, Don't give them away to goodwill, and don't try cleaning them with any modern "record cleaners."
I think these would be considered collector's items.