Aliexpress
Here are coupons that you can use.
Latest coupon code price check (UTC time):
Banggood
Banggood warehouse is located in China. There is one great coupon!
Link: Banggood product page
Coupon (210.99 USD): 7bcdf9
(CouponsFromChina.com tip: apply it 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): BGOCKV, aff7off, BGBFAFF2019, BGCITYADS2019, bGpAnDacHeCk, 2020CNY, BGVDay10%off, BGHOMEAPP, BGMPB2020, bGhOnEy10, BGAFF7OFF, BGSS10%SW, bgshOOp10, BGHome15%, BGHOMEAPP13, BGHOMEA13
(you can check these old coupons out, but these probably won’t work)
Price history and price alert
Do you need price history chart (for all/most countries) for Xiaomi OCOOKER Barbecue Microwave Oven 20L? There we go.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).