In a bid to increase market share, announced last Monday that it would take on Amazon by discounting its print books at least 10% below Amazon’s prices. Overstock, best known for selling products other than books, has been selling print titles for some time, but has yet to make such an aggressive cut to its pricing of titles. "We’re having a great year and want to thank our loyal customers for making it happen," said CEO Patrick Byrne in a press release. Byrne added that the move "immediately affects hundreds of thousands of titles."

Because Amazon and Overstock's pricing war took shape so recently, it is not yet known how the move has affected sales at many independent bookstores. Overstock sells 450,000 titles, but the promotion doesn’t apply to every book. According to Overstock spokesperson Judd Bagley, who described the response from Overstock customers during the first week as "impressive," the Amazon and Overstock overlap on 360,00 titles and all 360,000 were discounted. She said in aggregate, sales on the discounted titles have doubled in the week. In comparing both hardcover and paperback bestsellers, it’s clear that Amazon is determined to not be undersold, even if it means discounting some titles by over 56%.

This showdown between Overstock and Amazon is reminiscent of the holiday battle over ten bestselling books between Wal-Mart and Amazon in fall 2009 because it's the most significant example of two retailers going head-to-head with deep discounts on hardcovers. Both Wal-Mart and Target, as well as the largest bookstore chain Barnes & Noble, are sitting this one out. That’s not to say that none of them discount bestsellers online. For hardcovers, Wal-Mart regularly offers a whopping 49%.

Below is a sampling of bestsellers (alphabetical, by author) from a number of publishers in a variety of formats, with current prices at a variety of outlets:

* Inferno (Doubleday) by Dan Brown
List price: $29.95 hardcover
Amazon: $11.65, 61% discount
Overstock: $11.65, 61% discount
B& $16.82, 43% discount $14.57, 49% discount $17.99, 40% discount

* The Perks of Being a Wallflower (MTV) by Stephen Chbosky
List price: $14 paperback
Amazon: $6.09, 57% discount
Overstock: $6.09, 57% discount
B& $11.20, 20% discount $7.19, 49% discount $11.20, 20% discount

* The Great Gatsby (Scribner) by F. Scott Fitzgerald
List price: $15
Amazon: $5.47, 64% discount
Overstock: $5.47, 64% discount
B& $11.92, 20% discount $7.70, 49% discount No discount

* Gone Girl (Crown) by Gillian Flynn
List: $25 hardcover
Amazon: $10.93, 56% discount
Overstock: $10.93, 56% discount
B& $14.04, 43% discount $12.84, 49% discount $17.50, 30% discount

The Cuckoo’s Calling (Mulholland/Hachette) by Robert Galbraith (aka J.K. Rowling)
List price: $26
Amazon: $15.20, 42% discount
Overstock: ----
B& $15.60, 40% discount $15.19, 42% discount $16.95, 35% discount

* The Fault in Our Stars (Dutton) by John Green
List price: $17.99 hardcover
Amazon: $6.55, 64% discount
Overstock: $6.55, 64% discount
B& $9.99, 44% discount $9.24, 58% discount $11.98, 33% discount

* And the Mountains Echoed (Riverhead) by Khaled Hosseini
List price: $28.95 hardcover
Amazon: $12.04, 58% discount
Overstock: $12.04, 58% discount
B& $16.08, 44% discount $14.87, 49% discount $17.99, 38% discount

A Game of Thrones— 4-book boxed set of mass market
(Song of Ice and Fire series, Bantam) by George R.R. Martin
List price: $35.06
Amazon: $15.01, 58% discount
Overstock: ---
B& $21.03, 41% discount $19.78, 45% discount $21.03, 42% discount

* Lean In (Knopf) by Sheryl Sandberg
List price: $24.95
Amazon: $9.09, 64% discount
Overstock: $9.09, 64% discount
B& $14.33, 42% discount $12.81, 49% discount $14.30, 43% discount