Amazon teamed up with AT&T in order to offer a unique price for the Kindle 3G: $139. This special price is $50 lower than the usual one and comes as a follow-up to the enthusiasm in the AT&T team, with the carrier’s CEO Ralph de la Vega saying that the 3G Kindle is “by far the fastest growing connected device” on the AT&T network.

What’s the trick with this special offer? Well, the device comes with ad sponsored content, so the idea is pretty nice and a win-win situation. Users will have ads displayed at the bottom of the screen and can even select between them using the AdMash Kindle app. Back in April there was another hot offer, selling the Kindle WiFi for $114 and quickly making it the most popular and best selling eReader.

Kindle 3G also comes with several other offers: free 3G wireless, global 3G coverage, Kindle Store with over 950k books and integration with “Buy Once, Read Everywhere” Kindle apps.