The point is that if you instead of saying no ask a lot in return, you either get a great reward, or "get off the hook". If it's not a quid pro quo type of relationship, a personal relationship for example, I guess this does not apply (just say no =).
Edit: typos, missing word
- Don't say no to clients "crazy" demands, just calculate what it would actually cost, or what you would need to do what they ask, and quote them that.
- A good price is when you are OK either way: You're OK if they say yes, and OK if they say no.