i just bought this from amazon, http://www.amazon.com/gp/product/B005NGKR54/ref=oh_details_o00_s00_i00, and several other people in the forum have it. It actually has a power port adaptor that works with the pineapple. Here is a picture showing it powering the pineapple, usb drive and Evo 4G for tethering.
http://www.flickr.com/photos/98946258@N00/7656776166/