You're saying that time is valuable. The cost of the book is the dollar price + the time to acquire + the time to read it.
You're saying that the middle cost is significant. That suggests that the latter cost is also significant. Therefore lowering the dollar price of the book has little effect on the total in the above equation.
You're saying that the middle cost is significant. That suggests that the latter cost is also significant. Therefore lowering the dollar price of the book has little effect on the total in the above equation.