How to get rich buying and sellings used books Today I went out just to buy stuffs, mostly used books, which I just love to do. There are a lot of used books sellers in the center of Sao Paulo. However, this post is neither about books nor shopping, but it is about how economics and people work together. After leave my apartment, I went to my favorite book seller and as I got over there came up a girls selling to the the store's owner a buch of good books, all in "like new" condition. One of them was a french grammar book, which I instantly became interested in. To my surprise, all books -- maybe 14 or 20 books -- was bought by the store's owner for just $30, including the french grammar book. After the girl take their money I asked the store's owner how much the grammar is gonna to cost and he asked me to wait a few minutes to him examine the book and evaluate the price. I said OK and 10 minutes later he said the price was $40!