Horrified? It sounds like a donation win to me. The library got new funds that they can use to run operations, buy new books, etc., and some buyer(s) got books they really want to have.

It's kind of the Winchester Family Christmas Tradition principle:

> "Your generous gift and insistence that it remain anonymous touched me deeply. The candy would've brought great joy to the children for a few moments, but on the black market, it was worth enough rice and cabbage to feed them for a month."