Well, we don't agree about ownership. Gaugin and Van Gogh made the painting and there is a connection between the art and the artist, but I believe the piece belongs to the viewer. Ownership does not depend on who paid for it or holds the deed, or who made it. When I view a print, it belongs to me. Even if I can't take it home, I can crop it, dodge and burn it, etc., in my mind.
I don't see any real difference between a print on this site, or in a gallery or museum. In each case, the image is being put forth for public viewing. In that context, the viewer takes ownership and attaches whatever meaning or worth he chooses, for what ever reason.
Purchase seems to be somewhat inversely related to the artistic value. The worse the art, the cheaper it will likely be, and the more people can afford it. They may actually buy the cheaper piece because it is as good as they can afford. And then there are pieces that regardless of price, some art just won't move - couldn't give it away.
I don't understand how the evaluation of the work depends on whether it remains in view or is stored away. Some very fine art is in the hands of private collectors who hang the work in their home for pretty much their own pleasure. Some very poor art is displayed quite publicly. I don't see how that changes the value or the relative value.