O'Reilly's library is $499/year, or $75/year (with some other resources) if you're a professional member of the ACM which is, apparently, $99 per year (I didn't know the base cost until just now, I've been a member for years but have other things added on that push it past $99). I'd recommend that versus buying specific books since pretty much every worthwhile, non-open-access, technical book on software I've needed has been in there (not all, though). That $75 also gives you access to Pluralsight (I have mixed opinions on their courses, I wouldn't pay for it on its own personally but it's not bad if it's included in something else like here) and Percipio (never used it, can't comment).

So $174, toss in ACM's digital library for another $99 to go to $273 and you have $127 left each year for specific books you find to be worthwhile and want a hardcopy of or for other things. (It's actually cheaper for the first year with the link I posted below, but you should plan on the full price for the future.)

https://www.oreilly.com/online-learning/pricing.html

https://services.acm.org/public/qj/keep_inventing/qjprofm_co...

my Safari books (oreilly.com) online subscription! https://www.oreilly.com/online-learning/pricing.html

Just looked it up and the website is showing me $49/month or $499/year.

https://www.oreilly.com/online-learning/pricing.html