Reading an excerpt I can see that the History of the Harpsichord, by John Koster, includes interesting details that one cannot find in other general works in the field (such as Ed. Kottick’s), although they are generally available in papers by Koster.
In Europe it is available bound at a preposterous price €91,
and paperback (how good is the binding, who knows?) at much more reasonable €27 .
I spotted one or two reviews online, favourable but not very detailed.
Any opinions on this book?
I have full access to Cambridge Core and so can access the whole book, This is via my membership of the State Library of Victoria in Australia (free for residents). I am sure you can be a member of many other large libraries around the world to get the same access.
I have not read the book yet.
Being a member of large libraries in Ireland or in Italy is NOT easy.
You HAVE to be either a student or a teacher in the associated University.
I do not go to libraries: I read books online and, if they cannot be accessed online, I buy them, sometimes second-hand.
In Ireland they once gave me a one-month research permit in Trinity College (only place with a minimally decent musical stock), only applicable to a physical visit, not to online material, and NOT renewable for the rest of my life! 
Once there, I was able to see that, in the field of Early Music Performance, my three bookshelves had a better material than the Trinity College Library.
In Italy it is even more difficult.
“Forgedit!”. Thanks.
Edit: I meant my bookcases, with a total of about “8 meters of books”, not including musical scores (another similar amount).
Just in case, I re-checked the only University in Tuscany (where I am a resident which should give me some rights) with a sizeable musical contents: University of Florence.
https://unifi.libanswers.com/faq/192075
I translate an excerpt:
You can attend as utente esterno autorizzato
Ask via email to the specific library.
Gli utenti esterni autorizzati non hanno però la possibilità di consultare le risorse elettroniche in abbonamento (riviste on line, banche dati) fuori dalla rete di Ateneo.
Clearly, then, nothing outside the specific library.
And the original was in Swahili, or what? 
David
Sorry, I only translated the first sentences, the rest is clear in its original “Bureaucratic Italian”, a particular language that resembles Italian in grammar and syntax, but is completely different in vocabulary.
Here in Italy if anybody spoke it, it would be received by general laughter, yet is used in all written communication, including things as plain as wine labels!
Le 02/05/2024 13:03, Claudio Di Veroli via The Jackrail écrit :
paperback (how good is the binding, who knows?) at much more reasonable €27 .
I spotted one or two reviews online, favourable but not very detailed.
Any opinions on this book?
I have the paperback edition and the binding is still in good shape. But
this might have more to do with the little use I’ve had of the book than
with the quality of the binding. I don’t believe an expert like you will
find much that is really new. I did enjoy Paul Poletti’s article on
Temperament and Tuning, though.
Thank you Dennis, much appreciated.