I somewhat agree with the marginal costs argument.
However, that assumes that the work was done on commission or that the costs to produce the initial version was somehow covered. It also assumes no time is spent developing contracts, maintaining the tools needed to deliver the product, talking with the potential buyer, or starting threads to see what one should pay.
Further, the number of hours spent working learning photography is usually better described in months and years. And often uncompensated. Other professions generally get paid for much of their training.




