US online bookseller Alibris said it had launched a special offer to buy used copies of the new “Harry Potter” book for $ 5 as it seeks to meet demand for the most eagerly awaited book of the year.

British author JK Rowling’s sixth book about the young wizard, “Harry Potter and the Half-Blood Prince,” is scheduled to be released on July 16 amid a huge global publicity blitz and more than 10 million copies are ready for sale in the United States alone.

Alibris, which normally buys used or remaindered books from libraries and bookstores, is targeting parents whose children pressure them into buying more than one copy of the book so that all siblings can read it on the day of the launch.California-based Alibris has posted a notice on its Web site offering to buy used copies for $ 5 and to pay the postage. Chief Executive Marty Manley said it was the first time the company had appealed directly to readers in this way.

“I have two boys, a 9-year-old and a 13-year-old, and I’m sure I’m going to be buying two books so I’m going to end up with one extra,” he told Reuters.“It’s a test,” Manley said. “With this book it wouldn’t take a very large share of the primary market to get the secondary market going,” he said, adding that by the time Alibris pays around $ 4 for shipping, his total outlay is $ 9. Manley said the sale price would be determined by demand but would clearly be lower than the cheapest online offers for new copies.Parents hoping to return excess copies should be careful to stop their children fighting over the books — only copies in “very good condition” will be accepted.