I wish I were a better disciple of this philosophy. But it is hard to develop a feel for the subject without experiencing different quality levels, eras and countries of manufacture. Leave room for a few mistakes. Most hats can be resold to recoup most if not all of what you paid. Any shortfall is the price of tuition.
You offer wisdom here, Alan. Folks new to vintage hats would be well served to take this advice since these words will get them well and truly on the right road to a good collection.
A