My favourite painting of all time "The Escorial from a foot-hill of the Guadarrama mountains" by Lucas van Uden [
https://data.fitzmuseum.cam.ac.uk/id/image/media-4256550851] is quite a small painting that I'm sure most people have never heard of, hell, I'd never heard of it before I found it tucked politely in a corner of the Cambridge Fitzwilliam Museum, and I sure as hell don't know who Lucas van Uden is. Nevertheless, it is a remarkably beautiful painting and demonstrates true craft from the artist. I have no idea what a painting like this would cost, but I can't say it would be worth much compared to some of the other pieces in there. Your comment leads me to wonder what the incredibly wealthy would have to say about this painting's quality. It certainly feels worthy to me.