Aliexpress
Click here… to search for Xiaomi ZMI 3000mAh Power Bank Blue on Aliexpress
Here are coupons that you can use.
Latest coupon and price update (UTC):
Banggood
Banggood warehouse is located in China. There is one coupon available! Pretty cool, huh?
Link: Banggood product page
Coupon (8.36 USD): aff7off
(CouponsFromChina.com tip: paste coupon code in your cart and click Apply after clicking “Proceed to checkout”. Click to copy code and open shop)
Old coupons (from the oldest to the newest): PCNETWORK, e2bcea, 2019SPEDM, BG3CSUM, BGaDmITAd, bgchinafest, BGBFCR02, BGCITYADS2019, bGpAnDacHeCk, 2020CNY, BGVDay10%off
(probably won’t work, but you can try them out)
Price history and price alert
Check out price history chart (for all/most countries) for Xiaomi ZMI 3000mAh Power Bank Blue.
Price records source(s): Gearbest, Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).