krustynobb exactly, honestly not worth it, for example 200 soul stone to unlock priveliege and 5 advanced chapter (book I'm reading only costs 4 soul stones so total is 20). Adding on to the fact that you have to pay for the subsequent 4 souls tones for the next chapter? Not worth it.
What would be better is instead of this whole priveliege thing, allow the option to buy more chapters in advanced e.g. Next 5 chapters that hasn't been released at a cheaper price.
Or a buy 10 chapters for the price of 8 chapters total