Aliexpress
Here are coupons that you can use.
Latest coupon and price update (UTC):
Banggood
Banggood warehouse is located in China. There is one coupon available! Pretty cool, huh?
Link: Banggood product page
Coupon (246.99 USD): 7bcdf9
(CouponsFromChina.com tip: 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
Old coupons (from the oldest to the newest): Wholesale20, BGHOMEAPP, BGAFF7OFF, BGHCLE15, bgshOOp10, BGHome15%, BGHOMEAPP13, BGHOMEA13, BG11SHOP
(probably won’t work, but you can try them out)
Price history and price alert
Here is price history (for all/most countries) for Xiaomi Muggle HH6 Electric Mop.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).