We give our daughter a quarter for every hour she spends reading. She puts this money into her "Book Money" jar. She is only allowed to use this money to buy books.
When she brings home a Scholastic Book Order from school or asks to buy a specific book, she can use the money from her Book Money Jar. Sometimes she comes home requesting a specific book and we can purchase it from Amazon with her book money. This rewards and encourages her reading and adds to our library. I feel it has been a wonderful way to motivating her love of reading by providing her a way to purchase books she loves!