Power bank or external battery case?

[teribithia]

My iphone 4S can not support whole day use as the battery nearly drain .

So I searched iphone 4S external battery in amazon and find Plush cartoon toys power banks AD below. The price is 29.99$ a little expensive as its 5200mAh.

The introduce is "it can be used a handbag Pendant with Li-Ion 5200mAh battery. ." There is no review in the product page, I am not sure it is really cool as

the description .

http://www.amazon.com/Constellations.../dp/B00DJ3DZK2 (avoild link, delet url space when past in IE)

Also I found a external battery case here :

Amazon.com: uNu Power DX External Protective Battery Case for iPhone 4S & 4 - MFI Apple Certified (Matte Black, Fit All Models iPhone 4 & 4S): Cell Phones & Accessories

The battery capacity is only 1700mAh but can be used as a case protector for iphone 4s

The image :


Which one I should bought or

do anyone find the similar high capacity like 10000mAh but cheaper one in ebay buy.com or amazon and other place?