However, if you want to support the publisher/teacher/dharma and get them legally for cheap, check out this website: https://namobuddhapub.org/zc/PDF
You can get books like 'Clarifying the Natural State' and 'Essentials of Mahamudra' for $1.25 each, both of which I recommend.
I am getting some of the other pdfs.
I confirmed that this website is legit as it is listed in https://www.shambhala.com/khenchen-thrangu-rinpoche-readers-guide/
"Namo Buddha Publications is a 501(c)(3) non-profit, all-volunteer organization, which was was established to collect and publish all of Thrangu Rinpoche's books, Audio teachings, Video DVDs, and practice materials. The royalties and sale of his books go to towards publishing Rinpoche's teachings and supporting his charitable activities. The goal of Namo Buddha Publications is to make all of Thrangu Rinpoche's books, audio CDs, video DVDs, and Dharma photos available to everyone at a reasonable price."