It depends on the price... I have Bens gasification books and they are amazing. Solar information is out there and much more common and a lot of it is really good. The components are also much more reliable then even a decade ago and much more user friendly. Do you need it? That is the question.
These are the worst of times and these are the best of times. And this is the best tiny ad:
It's like binging on 7 seasons of your favorite netflix permaculture show