Hisgadget via Amazon offers the Intocircuit T5000 5,000mah External Battery Pack for $19.99. Coupon code "SJ268T94" makes it $10.99. Plus, Amazon Prime members qualify for free shipping. (Non-members can spend over $35 for free shipping; otherwise, shipping adds $5.22.) That's the lowest total price we could find by $10. It features six connectors (compatible with most phones) and built-in flashlight.