X-Dragon via Amazon offers the X-Dragon 20,000mAh Portable Power Bank in several colors (Blue pictured) for $26.99. Coupon code "M35JPHSZ" cuts the price to $18.89. With free shipping, that's $8 off and the lowest price we could find. It features three USB ports. Deal ends February 28.

Update: The price has dropped to $24.99 before coupon, $17.49 after.