Aliexpress
Here are coupons that you can use.
Latest price update (UTC time):
Banggood
Banggood warehouse is located in China.
Link: Banggood product page
Coupon (17.99 USD): BGELIG0920
Coupon (18.99 USD): 13f142
Coupon (18.99 USD): bgshOOp10
(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): 502C6B, PICODICOM, bgssaff9, BGaDmITAd, BGXMMJSO, aff7off, BGXMEUP, bGpAnDacHeCk, 2020CNY, BGXMSK, BGAQ20, BGXMSCH, BGHOMEAPP, BGSMARTHO, BGXMPS04, BGTT10, bGhOnEy10, BGSM15, BGSMOFF, BGSAMRTH
(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 Mini Power Strip 3 Sockets White.
Price records source(s): Gearbest, Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).