Literature and Capital – a still unsolved problem: how lemons turn into lemonade

According to a highly reputable POD service, the cost for producing a single copy of a certain book is 3.48$. The publisher sells it by 6.50$ (plus shipping costs) and the author is supposed to earn 1.21$.
A world famous online store sells and delivers a single copy by as little as 1.56$ (including shipping costs).
How do lemons turn into lemonade?