NEW YORK (AP) - The book price wars are no longer just for pre-orders.

Amazon.com was offering hardcovers of John Grisham's "Ford County" and Barbara Kingsolver's "The Lacuna" for just $9 on Tuesday, the official release date for both books. Hardcovers generally have a list price of $24 or higher.

In mid-October, Walmart.com announced dramatic discounts for pre-orders of "Ford County," Sarah Palin's "Going Rogue" and other popular November publications. Wal-Mart.com initially charged $9 for the books, a price quickly matched by Amazon.com, then dropped to $8.98 by Wal-Mart.com.

Authors, publishers and rival booksellers worry that cutting the price so low will harm competition and force down the cost of books overall, leading to a reduction in author advances.

On Tuesday, Walmart.com was selling "Ford County" for $12 and "The Lacuna" for $13.50. Another price cutter, Target.com, was selling "Ford County" for $15 and "The Lacuna" for $18.89.