Flavio:
I am quite sure that Simon Galley was telling the truth when he confirmed that it cost Harman more money to buy the backing paper for a roll of 120 film than it did to make a single roll of 120 film. The reason that the film part of the equation is smaller is that when you make lots of film you can bring down the per roll cost.
Just as he was telling the truth when Harman relatively recently invested substantial amounts of capital to buy the machinery to make their own 35mm cassettes, because they were having trouble with the cost and reliability of the available suppliers.
The problem with any of these components is that each of them is only inexpensive if one is using them with some economies of scale.
If Ferrania makes high volumes of film, the cost of the film per roll will be small.
Same goes for film cassettes, film boxes, shipping, customer support, property taxes, electricity, water, salaries, etc., etc. - the per roll costs depend heavily on how many rolls are involved.