Derek Sivers offers mountains of value at no cost to you.
More specifically, writers, here are his notes on the classic, On Writing Well.
And this blog post: $250K books sold. $250K to save lives.
Here are Goodreads comments on his book, Hell Yeah or No: What’s Worth Doing. I don’t see the book listed on Amazon, despite the Amazon link on the Goodreads page. It didn’t turn up in Apple Books either, so I think he’s simply selling it on his site. Sounds good to me.
Even better than the comments, here is his overview of the book. (Feels more like the entire book. Hey, I’m not complaining.)