$100 for a ACM membership $500 for O'Reilly. I can see why O'Reilly didn't want to renew. Learning materials are pretty slim with O'Reilly removed.
I dont see myself supporting OReilly at that price especially when they run at least once a year a 50% discount (black friday).
ACM offers other sources for books, not as complete catalogue but skillsoft has Manning Publications and No Starch Press, so from IT point of view, already great. I might miss the conference and some books there and there, but what is available is already great. Libgen/youtube and the like will cover the remaining.