portable 2200MAH Universal External Back Up Battery with Built in LED for 3.99 + free shipping
CABLE-MIX via Amazon offers Prime members its yubi power Mini Portable battery 2200MAH, for $7.99 with free shipping.
Coupon code "H8M23C8O" cuts the original $7.99 price to $3.99 (enter code at check out)
Note: the powerbank battery works for all phones and tablets
Shipping is free for Prime members (free student accounts available) or if you spend $35 or more.