Aliexpress
Click here… to search for Xiaomi Diiib LED PP Toilet Seat on Aliexpress
Here are coupons that you can use.
Latest coupon and price update (UTC):
Banggood
Banggood warehouse is located in China.
Link: Banggood product page
Coupon (119.14 USD): Terence
Coupon (120.42 USD): BG00c906
(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): BGDIB15, AFfbG10, BGBFAFF2019, BGCOVE30, BGCITYADS2019, BGDBII51, BGBAPOHG, BGDIIB39, BGHOMEG12, BGAFF10OFF, BGTT10, bGhOnEy10, BGdragonBoat, BGSS10%SW, bgshOOp10, BGCNDiiib, BGCNDIIIB15%, BGHome15%, BgcLuBofErtA10, BGCuponation10, 13f142, BG10OFFAFF, BGwhielabel, BGJUN215, 7bcdf9, BG10OFFAFF1, BANGGOODSD, BGAlerabat1
(you can check these old coupons out, but these probably won’t work)
Price history and price alert
Here is price history (for all/most countries) for Xiaomi Diiib LED PP Toilet Seat.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).