Aliexpress
Here are coupons that you can use.
Latest coupon code price check (UTC time):
Banggood
Banggood warehouse is located in China.
Link: Banggood product page
Coupon (68.39 USD): AFfbG10
Coupon (68.39 USD): BGBFAFF2019
Coupon (68.39 USD): BGCITYADS2019
(CouponsFromChina.com tip: coupon code has to be applied in shop’s 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): BGMOSCO2, TTxBG10, bgssaff9, BGCO1583, BGCOMO49, 502C6B
(these codes were not working in latest coupon update, but you can check them out anyway)
Price history and price alert
Check out price history chart (for all/most countries) for Xiaomi Cokit DYT-08 Mosquito Killer Lamp.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).