The book is for sale for ten pounds on the Oxfam website. Looks like the ebay seller found this book in a sale or something.
I don’t see why they can’t ask a reasonable price. They put a little time and effort into listing and posting the thing, they could’ve just recycled the thing if they were done with it, and OP could’ve looked around and gotten the book for cheaper.
I think this mildly infuriating because OP clearly missed a good sale, but this isn’t bullshit.
You say you stick to open source, do you happen to block your messenger apps from using Play Services? I know from experience the fallback notification delivery mechanisms of a lot of apps will keep the radio on for much longer than it would be with Google Play Services, so I wonder if that could make up for some of the difference.