New book sales may be struggling, but sales of used books are on the rise. According to a new study, “one out of every 10 book buyers bought a used book in the last nine months. One of the few growing areas of the retail book business, used books now account for about $533 million in sales annually — 13% of overall book units sold and 5% of total revenue — and could lead to as much as $1.5 billion lost in new sales.”