Aliexpress
Click here… to search for Xiaomi Youpin VIOMI YM-R4001A 4L Heating Water Bar on Aliexpress
Here are coupons that you can use.
Latest coupon code price check (UTC time):
Banggood
Banggood warehouse is located in China. You can get coupon down below.
Link: Banggood product page
Coupon (147.67 USD): bGhOnEy10
(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): BGMPB2020, BGHOMEAPP
(there’s a little possibility that old coupon will work)
Price history and price alert
Price history (for all/most countries) for Xiaomi Youpin VIOMI YM-R4001A 4L Heating Water Bar is here.
Price records source(s): Gearbest, Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).