[prawn]

"Two, the monetary cost of a book isn't the largest "cost"."

Is that going to be true for all people around the world, regardless of income? Sure it's probably true for you or I, but free learning resources are likely to be vital for many others.

[sweetjesus]

I don't think PP worded his point as clearly as he could but I think he meant something more along the lines of "a small list of free books that is vetted for quality is much more valuable than a big list of many more free books that includes duds". There is an intersection between that point and the point you made/and responded to which is, "some books (and therefore vettings) are so valuable they might be worth paying for over a less good free alternative" ... of course weighted for the amount of disposable income a person might have.