Yesterday was full of excitement in the e-book reader world. First, Barnes & Noble introduced a Wi-Fi only version of its Nook e-reader , and also dropped the price of its 3G device to $199. But  Amazon was not to be left in the dust, so it dropped the price of its Kindle e-book reader from $259 to $189 . Take that, Barnes & Noble!

Poor Borders wants in on the e-reader action, too. But, since the Kobo is so new ( PCMag reviewed it on June 17), and it's hard for its price to be dropped so quickly, Borders is offering other incentives. Announced today, with the purchase of a Kobo , customers will receive a $20 Borders gift card, and also double Borders Bucks that can be used towards a future Borders purchase.

The Nook may be $199, and the Kindle $189, but the Kobo is priced at $149, winning the title of cheapest e-book reader. But is it the best? Make sure to read PCMag.com's reviews , and decide for yourself.