Newegg.com has Rosewill 11200 mAh Powerbank (RCBR-13020-BK) for for $26.99 - $20 Rebate = $6.99. Shipping is $0.99, otherwise shipping is free with Newegg Premier.

Optionally, you may buy a quantity of 2 for $41.98 - $40 Rebate (2x $20 Rebate) = $1.98. Shipping is $1.92, otherwise shipping is free with Newegg Premier.