I just created this account to see what the fuss is about and check the price for the Spirit Stone. So I did a simple math:
Kindle version of Words of Radiance on Amazon cost $8.54, that is 483,000 words book edited by layers of professional editors.
And if you spend $9 on QI to buy Spirit Stone you get 1500 stones, 1000 out of 1500 stones has EXPIRATION DATE so you actually only buy 500 stones permanently. I will pick RTW here as example since it's one of Premiums on QI. 1 chapter of RTW cost 7-8/chapter, so 1500 stones only able to unlock less than 215 chapters, around 350,000 words, translated and edited by some random people on the internet and we have to deal with typo, grammar mistake, and hardheaded translators who keep using pinyin.
There might be some mistake but I'm here because I have some free time and did some simple comparison between price here with the price of an actual Premium Ebook on Amazon. If you have some correction feel free to correct me, I will post this thread on NUF too.