Yoobao portable charger is quite affordable in Qoo10 and is authentic based on the number of reviews given.
IMO, no point buying hand phone stuff at Taiwan, especially casings. All their casings can mostly be found in Qoo10 and they are selling at a much higher price. Example, the mercury diary case, qoo10 is selling at about $8. When I was there, the cheapest i can find is around $9 (which is at Keelung night market). The rest of the night markets or XMD are selling at around $15.