When interested buyers bid on a work of art they don't expect to pay a cookie cutter price of 99 cents. Various amounts of work go into creating a work of art. Some works' value is greater than others on face value alone. Of course, this is determined in the eye of the beholder. I will not cover the landscape entirely in this post. This is merely a thought I wanted to share to spark brush fires in the minds of the like-minded.
There are many reasons that could argue why music has become customarily priced at 99 cents per song. (Of course, iTunes. I won't go into the history of that here.) One reason may be that songs can now be easily replicated in identical quality. Which is difficult to do with paintings or sculptures. This is great for distribution, but the more a song is replicated, the supply grows, which makes the work of art less scarce, therefore less valuable on a per unit basis.
I don't have time or the brain space to analyze every facet of this inquiry. Just throwing it out there. Feel free to further ponder this and throw your 2 sense into the 99 cent phenom.