Thanks for the feedback. I see where you are coming from.
I think it is acceptable for any collector to want to gauge the value of their art pieces.
When collectors or dealers estimate the value of their pieces, what criteria do they go by? Artist, title, art type (covers, pages, etc), historic relevance, etc.
Covers, splashes, pages, etc are more common than corner box art. An artist can do multiple covers for a title. They will most likely do multiple splashes and many pages for a title. But they may only do one corner box piece.
So should corner box art only be compared to corner box art by the same artist? and in the same era? and for the same title?
What if the artist doesn't produce any other corner box art for the same title in the same era?
Then what could an owner of a corner box piece use to appropriately gauge the value of his art?