There's often deals on HumbleBundle, but they aren't always aimed at security, and even some that are aimed at security cover cloud and certifications which might kot be of interest to you. Some like the automate the boring stuff with python are available for free, I don't know of others but there may be, worth a search. Other than that, I don't know, but I can recommend their books. I've only heard good things about them, and the bits I've read (I got some system administration books from them and one for APIs) have been great. Although I think HTB/Academy may be better value for money at your stage. They're always great, and much cheaper. With a student subscription you can get access to the CBBH/CPTS modules for about 10 euros a month. Also I wouldn't recommend buying from the cheap guy that you know is pirating, you would essentially be encouraging that kind of behaviour, and you'd be better off pirating them yourself than paying someone else to do so for you. I know it's pretty hard getting stuff lime that in a poorer country, but that's life. I personally did pirate stuff when I was in the same situation (mostly games), but now I've got a job and can afford to pay for it and support the people. More on reddit.com

I buy NoStarch Press books from Humble Bundle where they have frequent bundles. The PDFs are all printable and not restricted. More on reddit.com

No Starch books have good writing and good editing. Generally worth even physical copies if you see a topic that you're interested. Comparable to O'Reilly and a couple steps up from Packt.

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The author, Dave Taylor , has been writing Bash/shell articles for the Linux Journal for a loooooong time and I certainly think he knows his stuff. There's an interview where he talks about "Wicked Cool Shell Scripts", and among other things he says the book isn't about teaching you shell programming - you're already set on a good course with the BashGuide for that - but about going "right into the meat of things". I've bought the book as well when it was in that recent Humble Bundle, but I haven't read it yet - will do so very soon, though. My guess is that there are many worse things to read, so I say go ahead and read it :) Edit, 5 days later: I've started reading the book, and while some scripts are interesting, I'm mostly underwhelmed and annoyed by the proliferation of bad practices, such as so many unquoted expansions and useless use of external commands such as sed and cut when Bash parameter expansion is perfectly capable of the job. More on reddit.com