Collectibles are very tricky. You want to buy something that isn't a fad. Like a movie prop, you'd want to buy the 100% most legendary movie that is timeless, like something from Casablanca, that has been appreciated decade-after-decade as worthwhile and valuable across many generations and fads. I wouldn't buy an expensive sports or trading card. Something related to Western culture is much safer, like the Magna Carta, or a founding US-related historical document. It's very hard to predict what will remain valuable decades or centuries out, so if something is still valuable now after centuries, it is likely to remain valuable