Depends on the type of book. Do you mean a new book?
The price of a book in 1950 varied depending on the particular type of book. Most books cost less than $5 in 1950.
The first Harry Potter book was not issued until 1997. Given the lack of availability of time travel in 1950, it would be likely that the cost would be infinite.
how much did a slinky cost in the 1950s
it cost $17.50 just for a skirt for a poodle in 1950.
cost of a bicycle in 1950?
It cost 12 cents.
it cost about 20 cents
2p
£25.00
a new home cost about 1,000 dollars in 1950
It was about 25 cents
About $500??