As previously mentioned, the library. The argument that one has to wait sometimes is superfluous. Anyone saying such a thing isn’t a regular library user.
Whatever is popular for the moment is just that: popular for the moment. It will pass. Almost never does a book need to be read the year it comes out. I mean, after all, if you value books, you value in-depth reading that provides perspective. As an example, when “Thinking Fast and Slow” first came out, getting it at even larger central branches was tough. Fast forward a few years and now every library has a few copies just sitting there. If one worries that if they don’t get it while it’s hot that it might be gone forever, then trust me, it probably wasn’t worth your time. The quality good books (both fiction and non-fiction) stay in the library system decade after decade.
If you aren’t familiar with intra-library loans, learn how they work. Super easy and you can get the books that are older, but not as heavily stocked, quite easily.
On tech books, get access to your nearest university, ideally a tech university library. Most will get you a card with certain conditions - and nearly all will let you visit and read forever with no questions if you’re professional about it. There are also private libraries (sadly rare) and some have good tech collections. Tech gets old and useless quick which is why most public libraries don’t stock stuff like O’Reilly. Which may be helpful to think about the value of spending one’s time reading something that will be DOA in 5 years or less. But if you are committed to a particular tech track or need for work, buy the book. That’s the cost of professional improvement. Don’t try to millennial your way around that. If you use ILL though, you can usually still borrow tech classics like K&R.
The modernist clamor for “the new” is dumbing down recent generations. Maybe what people really need to do is to read the existing books in the stacks so they can stop wasting time and money chasing the latest hip and trendy best seller that will supposedly cure all our ills.