Aliexpress
Click here… to search for Xiaomi Amazfit Cor Smartband on Aliexpress
Here are coupons that you can use.
Latest coupon and price update (UTC):
Banggood
Banggood warehouse is located in China.
Link: Banggood product page
Coupon (53.99 USD): band10
Coupon (54.99 USD): 7d18f7
(CouponsFromChina.com tip: you should apply the coupon in your cart after clicking “Proceed to checkout”. Click to copy code and open shop)
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k
Old coupons (from the oldest to the newest): midong, midong48, e2bcea, cor50, 49amazfit, cor38, cor39, amazfit100, TTxBG10, BGss506, AFfbG10, 502C6B, BGcorHK, BGBFCR12, BGBFAFF2019, BGVDay10%off, BGBGAFF10OFF, BGCOR39, BGACMAY
(there’s a little possibility that old coupon will work)
Price history and price alert
Price history (for all/most countries) for Xiaomi Amazfit Cor Smartband is here.
Price records source(s): Gearbest, Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).