Some can be found cheaper...
...but TCOJCOLDS FREELY gives away their Book of Mormon.
(OTOH; I don’t know about their OTHER scriptures.)
Probably on the order of the Missal pricing. Some cheaper than others based on the paper used the cover and binding.
The triple combination leather bound with thin paper, is going to cost.
The Book of Mormon paperback printed by the tens of thousands in multiple languages, free in the sense that nothing is free other than perhaps salvation, as a free gift, and we all should know the cost of that gift to mankind.
Generally the D & C and the Pearl of Great Price are not free.