No, the cost of a book of stamps is the same as purchasing twenty individual stamps. Most people go ahead and purchase a book of stamps because they like to keep some at their homes. This avoids a trip to the post office each time they need to mail a letter. However, if you need to purchase a stamp of a different value, then you will probably want to purchase a single stamp. You likely do not need an entire book of stamps in an odd value, and the post office does not even offer entire books in some values.