But here's the problem: the very concept of "marginal cost of production" is nearly made obsolete by computers and the Internet. It used to be that the effort to produce the copies was proportional to the number of copies being made. Not any more. (Why else would we have spam?)
Maybe the real measure of value is the total cost of production. It used to be that total cost and marginal cost were pretty closely related. But in today's world, the amount of effort to create a work has stayed the same (apparent quality of said work should be ignored for the sake of this discussion), while the effort to duplicate or distribute said work has gone way down.
This is the same situation created by the printing press in the 1500s: it used to be that monks had to transcribe documents by hand in order to distribute them thus making scrolls and so on highly prized. Suddenly people could make many, many more copies quite easily. However, it still required individual effort to make each copy, so marginal cost of production still applied.
Radio and television upset the balance even further. Someone could broadcast a work just once, and it didn't matter how many people were watching or listening. But the market managed to twist a way to apply the idea of "marginal cost" by figuring out about how many people were tuning in, thus deriving an apparent value. Hence, advertising and the Nielsen ratings.
There's not going to be an easy answer to the problem.
It seems that more and more mathematicians are using a new, high level language named "research student".