Bought them for $1000-1500. I am not smart enough but perhaps you are. He has made many millions trading futures.
Selling them for $100.

True, the other way of looking at it is if your expected buyer domain is a dozen ppl, you have to price the book at 10,000 dollars to breakeven.If the publisher sells the book at a very low price,
the buyer would think the book content is of inferior / questionable quality.
If the publisher sells the book at a very high price.
then the buyers would think the book content is of superior quality.
if it is given to me free, I'd put it in the fireplace to keep my room warm.