PoweraddDirect via Amazon offers its Poweradd Pilot 2GS 10,000mAh Portable Power Bank in Black for $17.99. Coupon code "USJLUHMI" cuts that to $8.99. Plus, Prime members bag free shipping. (Non-members can spend $49 or more to qualify for free shipping; otherwise, shipping costs $5.99.) That's the lowest total price we could find by $7. It features dual USB ports and auto detect technology.