I went with the final option.
I buy books I disagree with by authors I disagree with, and I do so frequently. I do this in order to grow as a person, to develop a deeper understanding of views contrary to my own, and to generally support the free exchange of ideas.
That said, I find certain views reprehensible and unworthy of my investigation, and I won't purchase books promoting those views. For instance, I will not buy Tim Allen's
Don't Stand Too Close to a Naked Man, because it assumes that Tim Allen exists and is funny. This notion disgusts me.
