I sell copies of my book The Entrepreneur’s Guide to Sewn Product Manufacturing on Amazon’s website for $60 -that’s the retail price. When I was restocking my electronic inventory this morning, I noticed I had a competitor. This vendor (scroll down) is selling a used copy of my book in “good” condition for $100! Curious, I googled it and found another vendor selling it for $509.81! Evidently my book improves with age.