CowBoom offers the used Amazon Kindle Touch WiFi E-Ink 6" eBook Reader, model no. D01200, for $39.99 plus $5 for shipping. That's $24 under the lowest total price we could find for a new unit, although we saw it for $5 less a month ago. It measures 0.34"-thick, features a 6" 600x800 e-ink display, and weighs in at just under 9 oz. It also sports 4GB internal storage, 802.11n wireless, X-Ray (which downloads Wikipedia information along with your books), PDF support, and more.

Note: No warranty information is available. This used unit may be missing accessories and have scuffs, blemishes, or scratches.