After skimming through it a bit, and as a CS student, this looks like an excellent introduction to the theory of computer science, especially for someone with no background in it. It corresponds with what I would expect a first or second year university course on Computer Science would cover. After reading some of this, if you're still interested in this sort of thing, the rather infamous Introduction to Algorithms published by MIT press may be a good next step. PDFs can be found online with a bit of digging.
It's times like this that I forget how lucky I am to live downtown in a major city. Within 15 minutes walking distance from my house, I have at least 4 used book stores, 2 record stores 1 vintage/thrift store, and another 2 vintage clothing stores, all of which accept trade ins for cash or merchandise. If none of those places give me moneys for my useless crap, then I can just leave stuff on my sidewalk and it'll be gone in less than a day.
WHEREAS, if I lived in a suburban area, which I assume you probably do, finding anyplace this would be substantially harder to achieve, and ideas like the OPs/amazons, would actually be pretty awesome.
Or you could just walk over to your local thrift store every month and give them your shit. Or used book store. Or used clothing store. Or record store. Or...