Aliexpress
Click here… to search for Xiaomi Mijia Four Digit Power Strip on 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 (28.79 USD): BGSTHO15
Coupon (28.79 USD): BGHONEY2110
(CouponsFromChina.com tip: just apply this code in your cart after clicking “Proceed to checkout”. Click to copy code and open shop)
Old coupons (from the oldest to the newest): 2499XM, bgsport, 6OFFXM, affiliate6, 2019SPEDM, bgssaff9, aff7off, BGaDmITAd, BGAQ20, BGSAMH, bGhOnEy10, BGSM15, BGSMOFF, bgshOOp10, BGSAMRTH, BGELIG0920, BgcLuBofErtA10, BG15SH12
(these codes were not working in latest coupon update, but you can check them out anyway)
Price history and price alert
Check out price history chart (for all/most countries) for Xiaomi Mijia Four Digit Power Strip.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).