I don't know if that's enough of a measure.

There are many reasons to collect things, and many reasons to let go, too.

It's easy to think of a scenario where a collector sells an item for $8,000 and doesn't replace it but instead goes on holiday or whatever. (In a way, that's what it means for an item to "have" value.) Many of those perfectly valid scenarios would apply just as well to an insurance claim as to a sale.