For Humble Choice, the charity gets 5%, and there’s no way to adjust that as far as I know, so you’re worried about a whole $0.60 per membership, assuming you paid full price for the month at $11.99. If you managed to get it at $8, it’s $0.40.
If you’re going to be upset about something, save it for non Choice bundles, where you can actually adjust how much the charity gets.
And even then, if I have most everything in the bundle, I’m still not paying $25 or whatever for it.
What’s crazy to me in light of this post’s exchanges is that often these cheap keys show up a day or more after Choice or a bundle goes live, and there may be only one or two keys per merchant, so it’s entirely possible people are buying the bundles, and just reselling the keys separately to make a buck after the publishers and charities already got their cut. Maybe, or not.
Keyword filters are a thing