New ask Hacker News story: Ask HN: Best place to purchase (used) technical books that's not Amazon?

Ask HN: Best place to purchase (used) technical books that's not Amazon?
9 by slipperlobster | 2 comments on Hacker News.
I'm trying to disconnect myself from Amazon as much as I can. Where this burns me is purchasing (used) technical books. I've been trying to leverage my local library system more but the majority of the technical, CompSci-esque books are laughable. I found one book that's good and I'm working through it, but most of the stuff there is "Windows 8.1 for Dummies" and "Hosting your own blog" sort of content. I think the next most-technical book I've seen is I know there's the traditional MSRP avenues for new books, such as traditional book sellers, but I'm hoping I can find a marketplace for used, worthwhile technical books. Any pointers? Thanks!