I'm talking about things like https://www.amazon.com/Computer-Science-Overview-Brookshear-... (Brookshear & Brylow), which Amazon tells me is US$155.49 for the Swindle or US$79 in paperback (new) and is in its 13th edition after 35 years; the first edition was evidently in 1985, so they've averaged roughly three years per edition. As far as I can tell, the only novel work Brookshear has ever published (not counting textbooks and papers about teaching) was a two-page paper in 1978 on projective prime ideals; and Brylow is hardly a more accomplished researcher, having published a couple of papers about formal methods for real-time software in 2001–3 and a few less-cited papers up to 2012. However good the book was in 1985, I wouldn't consider teaching from it today.
Skiena's book is an example of a really good textbook. Brookshear's book is an example of paying more. I did try to find a book like that about algorithms and data structures, but unsuccessfully; the closest I could find was Brookshear's chapter 5, which spends 50 pages to cover Euclid's algorithm, sequential search, insertion sort, and binary search (as well as, lamentably, bubble sort), all in terrible Python and 1958-style flowcharts, while giving terrible programming advice and performance numbers so wrong they weren't even right in 1985.
It's true that this kind of thing is limited to entry-level courses and more popular majors, as far as I can tell. Upper-level STEM courses don't attract enough students for it to be worth the effort to rip them off this way, even for world-class ripoff experts like academic publishers.
India has a significant advantage over Perú, Egypt, or mainland China, in that English is a second language to most of its population but not a foreign one, so the translation obstacle isn't nearly as serious.
Buy an older edition on eBay and get problem sets from classmates or the library. This works well unless the publisher has some skeezy online component.
> So generally the textbooks you have to pay more for are the worse ones.
Not generally true. Maybe true for some subjects. My experience is that in upper-level STEM classes, there might be only one or two good books that you’d want to use.
For example, take algorithms. There are a couple good algorithms textbooks, one of them is The Algorithm Design Manual by Skiena. I can see that it costs $33 on amazon.com for a digital copy, but if I go to amazon.in it’s available for ₹866, about $11.50 at current exchange rate.
That isn’t even a specialized subject. If you’re in an advanced subject in an engineering field or one of the sciences there might be even fewer choices available.