Right now, you can pick up KMASHI's 10,000mAh battery pack from Amazon for just $11.99. But you can actually get it even cheaper if you use promo code - 6ACUX5E9 - which will drop the price down to $9.69. It also includes Amazon Prime free shipping. There's two USB ports here, one is a 2.1A, and the other is a 1A port. You can pick yours up from the link down below.
KMASHI 10000mAh MP816 (2.1Amp+1Amp Output,2Amp Input Fast Charging) Dual USB Portable External Extended Battery Pack Power Bank Backup Charger For iPhone 6 Plus 5S 5C 5 4S 4 iPad Air Retina Mini Samsung Galaxy S5 I9600 Neo S4 I9500 I9190 S3 I9300 S3 I8190 S2 Note 3 N9000 Gear HTC Sensation One X S EVO 3D 4G DNA Thunderbolt Incredible Droid DNANexus 4 7 10 LG Optimus V Blackberry Z10 Z30 Q5 Q10 Bold Curve Torch Motorola Razr Maxx Bionic ATRIX Nokia Lumia 1020 920 Google Glasses and other 5V Smartphones