I am looking for scientific research that has been done on how much it
actually costs to make visual art. The production cost per painting:
labor cost + material + fixed cost (studio rent etc.)or even the
opportunity costs. Preferably on contemporary art. I need the
information for a simulation experiment with art price indexes.

I expect that with a little thought you can figure out the
imponderables in your question:

1)  The price of pieces of art has a great deal to do with the
artist's market value, almost totally unrelated to his costs.
2)  Keeping it simple and comparing only painters:  some can slap-dash
their work quickly  - and still sell it for a good price -  while the
technigue of others is much more time consuming.  Let's say, one does
a piece a day and the other takes a week to finish.  Ok, the first one
floods the market, but still gets half the price of the second one for
his works, so  - like in any company -  his production overhead per
painting is lower.

Need I go on?

Art is not subject to scientific or economical research.

Grandma Moses did her thing with virtually no overhead, just the cost
of materials, just sitting at home where she would have been anyway.
Van Gogh painted his heart out and gave away pictures for a need meal.