Aliexpress
Click here… to search for Deerma DEM-F600 Air Humidifier 5L on 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 (43.87 USD): BGAFF10OFF
Coupon (43.87 USD): BGCuponation10
(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): BGE13, elec, BGVDay10%off, bGhOnEy10, BGTT10, BGSMOFF, bgshOOp10
(probably won’t work, but you can try them out)
Price history and price alert
Price history (for all/most countries) for Deerma DEM-F600 Air Humidifier 5L is here.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).