Aliexpress
Click here… to search for VIOMI DF01 6.6L 1500W Electric Water Heater on Aliexpress
Here are coupons that you can use.
Latest coupon and price update (UTC):
Banggood
Banggood warehouse is located in China. Well, there is one coupon available right now.
Link: Banggood product page
Coupon (140.99 USD): 7bcdf9
(CouponsFromChina.com tip: apply code in your basket (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): BGVMDF01, BGCITYADS2019, aff7off, bGpAnDacHeCk, 2020CNY, BGVDay10%off, BGHOMEAPP, bGhOnEy10, BGAFF7OFF, bgshOOp10, BGhome15%, BGHome15%, BGHOMEAPP13, BGHOMEA13, BGCuponation10
(there’s a little possibility that old coupon will work)
Price history and price alert
Do you need price history chart (for all/most countries) for VIOMI DF01 6.6L 1500W Electric Water Heater? There we go.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).