I worked for Goodwill years ago way before Ebay! I know some of the items that came though the store were worth a fortune but no way to certify them then. This was in Southern California and every so often an antique appraiser would come through the store and leave pictures of items he was looking for for his clients. Seeing all the old books coming through the store gave me the chance to study them and know which ones were rare or collectible. Some the binding is worth more then what the book is. I can find a book at a yard sale and know what it will sell to the book dealers on Ebay. I contact them, and don't bother with the bidding or listings.