Aliexpress
Click here… to search for Xiaomi Smartda Xiaoda 15W Charger 18W Cup Pad on Aliexpress
Here are coupons that you can use.
Latest coupon and price update (UTC):
Banggood
Banggood warehouse is located in China. I couldn’t find any coupon for this product on latest product update.
Link: Banggood product page
Price: -3 USD
It looks like this item is out of stock in Banggood. If you found it then please send me the link. I will replace it.
Click here to search on Banggood!
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k
Old coupons (from the oldest to the newest): BGVDay10%off, BGSAMH, bGhOnEy10, BGSM15, BGSMOFF, bgshOOp10, BGSAMRTH, BGAFF10OFF, BgcLuBofErtA10, BG15SH12, BGSTHO15, BGHONEY2110, BGSHOM15, 13f142, BGSHE15
(these coupons are old, so probably won’t work)
Price history and price alert
Price history (for all/most countries) for Xiaomi Smartda Xiaoda 15W Charger 18W Cup Pad is here.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).