Alright I've been eyeing on these for quite a while and this is the cheapest I could find… Banggood are selling the 5,000mah/16,000mAh for $20.94/$34.77 and Gearbest $17.75/34.14
As comments on OzB claim that the 16,000mah power bank and Mi Band are genuine (some proof here), I'd hope this one is too. However it's best to pay with PayPal in case anything goes wrong. Otherwise great deal especially for it's ultra thin form factor
Learn more about the Xiaomi Ultra Thin Power bank here
Technical Specifications:
Model: NDY-02-AM
Battery type: Lithium-ion Polymer rechargeable cell
Input Voltage: DC 5.0V
Output Voltage: DC 5.1V
Input current: 2000mA(TYP)
Output current: 2100mA(TYP)
Rated capacity: 3.75V/5000mAh(TYP)
Charging time: 3.5 hrs with 5V/2A plug and standard cable
Size: 125 * 69 * 9.9mm
Load detection: Auto-detects device plug-in/plug-out
Safety: Supports protection from over-voltage (input and output), over-current (input and output), short circuit, over-charge, over-discharge, and battery Positive Temperature Coefficient (PTC).
Out of power protection: Awake once pluged to the charger
Charging temperature: 0℃-45℃ (TYP)
Discharging temperature: Initial -20℃~+60℃(TYP)
Weight: 156g