Bay Psalm Book: Why the £18m price tag?

They already had psalm books, but being reformists who embraced congregational singing, wanted a translation from the Book of Psalms in Hebrew Scriptures that was both closer to the original and written in verse.
A printing press - perhaps obtained surreptitiously to avoid English licensing laws - arrived from London in 1638, along with 240 reams of paper.
Though the man who raised the funds for them, the Reverend Jose Glover, died during the journey, his widow settled in Cambridge, Massachusetts where she established the press

It was operated by Stephen Day, an indentured servant of the Glovers and a locksmith by trade. In 1640 he printed some 1,700 copies of the 300-page Whole Book of Psalmes Faithfully Translated into English Metre, commonly known as the Bay Psalm Book.

The simple volume was put straight to use by congregations across the colony. Though the text was reprinted more than 50 times over the next century, most first edition books were worn out within decades.
"It's a book that was not created to be fancy or splendid or valuable in any way other than the significance of its content," says Derick Dreher, the director of Philadelphia's Rosenbach Library, one of the few institutions to hold a Bay Psalm Book.
"But because the congregation for which it was created literally used the book to death, very few of the copies have survived.
"We have all sorts of reports that go well back into the 19th Century about the lengths to which people were willing to go to acquire a Bay Psalm Book and they just couldn't be had."