here's one I bought a few years ago for $$ only to learn recently it's now available for around $25. The book contains excerpts in English from Cardinal Cajetan. Cardinal Cajetan was one of the leading 16th century Roman Catholic theologians, and a direct opponent of Martin Luther. To my knowledge, this is the only major translation of his writings in English.
From reading through this book since I bought it 2010, I've learned to have respect for the intellect (and demeanor) of Cajetan. I might not agree with what he was saying, but he certainly was articulate.
I've also learned to no longer pay a lot of money for rare books. I keep getting burned a few years later.