iPhone external battery pack - Taipei

Looking for an iPhone 4s compatible external battery pack in Taipei.
Checked around many junk shops in Ximending and Daan, but I need it by Sunday so time to get serious with the search.

Could be a rechargeable brick or just something that uses AA batteries.

GuangHua Digital Plaza I would guess has a lot of stuff like this:

[googlemaps]25.045452,121.531779[/googlemaps]

http://tw.search.bid.yahoo.com/search/ac;_ylt=Aqoo4gAQgFX3a34x2mixlmj3_rF8?ei=UTF-8&p=iphone+4s+%E5%A4%96%E6%8E%A5%E9%9B%BB%E6%B1%A0

Should be able to find what you’re looking for.