Amazon with EC Technology has the EC Technology B30-MET22400BR 22400mAh Portable External Battery Pack / Charger (red/black, blue/white, red/orange or white) for $50 - $10 off with coupon code 2CTHM6P2 = $40 with free shipping. Li-ion battery can charge an iPhone 10-12 times, a Galaxy S4 5-7 times, or an iPad mini 3-5 times.
http://www.amazon.com/exec/obidos/ASIN/B00FDK2G2C?tag=vp314-20
http://www.amazon.com/exec/obidos/ASIN/B00FDK2G2C?tag=vp314-20