CowBoom offers the used Amazon Kindle 6" WiFi eBook Reader
in Graphite, model no. D01100, for $29.99
for shipping. That's tied with our February mention as the least expensive Kindle eBook reader we've seen. (It's also $54 under the best price we could find for a new one from Amazon.) It features a 6" 600x800 E-Ink display, room for up to 1,400 books on its 2GB internal memory (1.25GB available for user content), 802.11n wireless, and more.
No warranty information is provided. Also, this used item may have blemishes and be missing accessories.