Aliexpress
Here are coupons that you can use.
Latest price update (UTC time):
Banggood
Banggood warehouse is located in China.
Link: Banggood product page
Coupon (76.90 USD): BGLED07
Coupon (79.52 USD): Cuponation9
Coupon (80.40 USD): BG8ReviTrage
Coupon (82.15 USD): BG00c906
(CouponsFromChina.com tip: just apply this code 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): BGLIGHT2020, bGhOnEy10, BGAFF10OFF, BGdragonBoat, BGSS10%SW, bgshOOp10, BgoFErTaSchInA10, BGELIG0920, BgcLuBofErtA10, BGCuponation10, 13f142, BGHONEY2110, BG10OFFAFF, BGwhielabel, BGLIG12, BG10OFFAFF1, BGd0b05d, 00c906, ADMITAD2212, 2022ACTIESNL, Terence, BGLED2203, 2203ActiesNL, tRaDetRaCKeR, 8wEbgaInS5, pROMo8cuPoN, BGf94f14, BGLED2206
(I don’t think these’re gonna work, but you can try ’em out anyway)
Price history and price alert
Check out price history chart (for all/most countries) for Xiaomi Huayi Disinfection Sterilize Lamp 38W.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).