Aliexpress
Click here… to search for Xiaomi Camera MINI 4K Action Camera on Aliexpress
Here are coupons that you can use.
Latest coupon and price update (UTC):
Banggood
Banggood warehouse is located in China. Only one coupon available!
Link: Banggood product page
Coupon (89.99 USD): TTxBG10
(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): 4a5bd1, AlibuyBGMJ4K, e2bcea, 502C6B, plali01, ea5732
(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 Camera MINI 4K Action Camera.
Price records source(s): Gearbest, Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).