Aliexpress
Click here… to search for Digoo DG-M02 420ml Night Light Humidifier on Aliexpress
Here are coupons that you can use.
Latest coupon code price check (UTC time):
Banggood
Banggood warehouse is located in China. Only one coupon available!
Link: Banggood product page
Coupon (21.70 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): BGDG98, BGDG15, BGdigoo15, BGDigoo15%, 20%DG422, bGhOnEy10, BGdragonBoat, BGSS10%SW, bgshOOp10, BGHome15%, BGHALLOWEEN, BGHOMEA15%, BgcLuBofErtA10, BGHBHJ105, BGAFF10OFF, BGCuponation10, 13f142, BGHONEY2110, BG10OFFAFF, BGwhielabel, BGisZX163, BGISDC163, BGISD163, BG10OFFAFF1, BANGGOODSD, BGTYOT163, BGUdb72, BGTYOL163, BGUbf66, 00c906, BGAlerabat1, BGe22583, Terence, Tabby20, 2203ActiesNL, BG1efeb0, 8Couponsde, MVC8SPRING, 8BGwbg2204, tRaDetRaCKeR, 8wEbgaInS5, pROMo8cuPoN, BGJUNEGSG9, BG8ReviTrage, Cuponation9
(you can check these old coupons out, but these probably won’t work)
Price history and price alert
Here is price history (for all/most countries) for Digoo DG-M02 420ml Night Light Humidifier.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).