Charity Won't Contain This Secondary Market

Each year I receive about 10 introductory economics textbooks from publishers. The purpose is to induce me to adopt the book in my 500-student principles class. Many years ago the books I received typical copies, same as the students would buy. Book-buyers came around seeking to buy my unused copies, but I never sold them. Others obviously did, because the publishers started stamping “Complimentary copy” on these freebies. One publisher even has my name printed on the copy I received. The purpose of all this is to prevent an increased supply in the secondary book market from competing with the supply of new books. I received a text today that had stamped, “…please return it to XX and we will donate $1 to [a charity]….”
Heartwarming—but it requires me to spend time addressing an envelope, and spend the University’s money on mailing costs. I DON’T THINK SO, despite the worthiness of the cause and my desire to protect authors’ royalties. Publishers will have to do something better than this to cut supply in the secondary market.