An interesting market segment that has recently gotten definite heat are pop-ups from the 1960s. Those produced by Hallmark seem to be especially hot. I’ve recently sold several 1960s Hallmark pop-ups. Although their Haunted House is perennially popular, this 1960s graveyard pop-up is almost never seen. The fact that the original envelope is extant is a definite plus. It looks to be in very-fine-plus or better condition. This is definitely worth acquiring. I know this seller. He is a long-time collector and a truly nice person.
08/15 Update: I’m glad to see this fine pop-up fetched $280.