There is a small fee if you download over 3G. You can prevent that by setting the charge limit on your "Manage my Kindle" page to $0. Wifi is always free. (sou

There is a small fee if you download over 3G. You can prevent that by setting the charge limit on your "Manage my Kindle" page to $0. Wifi is always free. (source: http://www.amazon.com/gp/help/customer/display.html/ref=hp_left_sib?ie=UTF8&nodeId=200505520 http://www.amazon.com/gp/help/customer/display.html/ref=hp_l...)