Some book collectors care for rare books from the 1400's, termed "incunabula"

 Incunabula are the earliest printed books; they roughly cover the period 1450-1500.

Abebooks, a large search engine, has a dedicated webpage about what they are to the book collector:

The term Incunabula (also incunable or incunabulum) refers to a book, pamphlet or other document that was printed, and not handwritten, before the start of the 16th century in Europe.  The first recorded usage of the term incunabula came in 1639 when the noted bibliophile Bernhard von Mallinckrodt issued a pamphlet to mark the bicentenary of the advent of printing by movable type titled De ortu et progressu artis typographicae (“Of the rise and progress of the typographic art”). 

It was within this pamphlet he used the phrase prima typographicae incunabula, “the first infancy of printing” to describe books printed before the date 1500.

 (https://www.abebooks.com/books/rarebooks/gutenberg-printing-press-incunable/incunabula.shtml)