Would it be possible to make such a list with free and/or libre books? The list they made is not extraordinarily expensive but not cheap either. Some are outrageous: an introduction to partial differential equations for 110 GBP?!
One is that these books are not computing hardware. If you buy them used and take care of them they won't depreciate quickly. Just sell them a couple years later. If you find you need them again several years after that, Abe Books/Amazon will find them for you again.
The other is: Theoretical physics is hard, evil hard for most people. Don't handicap yourself with crappy tools. The difference between a lousy book [1] and a great book may be hundreds of hours, it may be frustration with the material that makes you want to cry, or it may be the difference between learning the material and hitting an impenetrable wall.
I should also warn you that I and my colleagues in physics routinely found that we had to sample a dozen highly-rated books in a given subfield before we found the one that gave us the insight into our particular problems. I picked up that many books on semiconductor optics - and my better-read colleagues tried many, many more papers than that - before finding Coldren and Corzine, which is a revelatory text. (And, for all I know, out of print now. The hell of becoming a world expert in something is that you wind up being part of a global audience that would fit in one or two buses.)
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[1] For you, at a particular time in your career, for a particular set of things you are trying to learn. Every book is is lousy to someone. The fact that there is no one-size-fits-all standard for books is just another reason why your physics education is going to require a bit of trial and error, fueled by a bit of cash.
I agree - some of the textbooks on there are extortionately priced.
I did put some free resources at the bottom of the article, although admittedly I could have added more. If you look at the link in the first comment there are some great lectures in there.
Leonard Susskind's Stanford Modern Physics lectures are fantastic. If you search on YouTube for Stanford/Susskind/General Relativity etc, you should be able to dig them out.
