Price history, coupons and price alert are available on this page. Best price?
Model: MJJSQ03DY, Power: 40W, Spray Volume: 450ml/h, Noise: ≤39dB, Voice Control: Yes (Only supports Chinese version), Water Tank Volume: 4.5L, Voltage: 220V/50Hz, Working Time: 10-25h, Purification Method: UVC-sterilization + Soft Water Resin Filter, APP Control: Yes, Spray Volume Gear: 3gear, Constant Humidity Mode: 40-70% + Over Humidity Protection
Aliexpress
There’re some similar (or not) items on Aliexpress
Click here to search by yourself. 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
1. ($127.50): BG1efeb0
2. ($128.89): Terence
3. ($128.89): 2203ActiesNL
4. ($130.27): BG00c906
paste coupon code in your cart and click Apply after clicking “Proceed to checkout”. Click to copy code and open shop)
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k and https://couponsfromchina.com/short/5cd
Old coupons (from the oldest to the newest): bgshOOp10, BGMJJSQ03DY, BGHome15%, BGHOMEAPP13, BGHOMEA13, bGhOnEy10, BGQ03DYRS, 7bcdf9, BGCuponation10, BG10OFFAFF, BGwhielabel, BG10OFFAFF1, 6GSGIT, 00c906, ADMITAD2212, 2022ACTIESNL, Tabby20
(probably won’t work, but you can try them out)
Price history and price alert
Do you need price history chart (for all/most countries) for Xiaomi Mijia MJJSQ03DY Humidifier S 4.5L? There we go.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood and Aliexpress (only if product name will be the same as on Banggood and I will post it on social media though, so it’s more like Banggood price alert)).