It all started last week when Wal-Mart slashed ten not-yet-published books to $10, as much as two-thirds off the cover price in some cases. Amazon.com matched Wal-Mart at $10, so Wal-Mart went to $9; Amazon matched them again, and the next move was $8.99.

At that point, as the Wall Street Journal reports, Target entered the fray, which prompted Wal-Mart to shave another penny off, bringing us to $8.98—and maybe lower a little later. ""It remains to be seen if we will go lower if the competition slashes prices further," says a Target spokesperson. "At the moment we are only matching what others are doing, but we're watching closely. We want to remain competitive."

So now Sears steps in and says it's not cutting prices on any of those books (beyond its usual discounts, we suppose), but as part of its new "Keep America Reading" promotion, you can show them your receipt for any of those cheap hardcovers from the other three stores, and Sears will give you up to $9 in store credit.