Aliexpress
Here are coupons that you can use.
Latest coupon code price check (UTC time):
Banggood
Banggood warehouse is located in China. You can get coupon down below.
Link: Banggood product page
Coupon (27.19 USD): BGSmart6
(CouponsFromChina.com tip: you should apply the coupon 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): BGGOS924, BGD11031, BGc8f5ec, BGB5040, ADMITAD2212
(there’s a little possibility that old coupon will work)
Price history and price alert
Price history (for all/most countries) for 2x Gosund SP1-H HomeKit Smart Plug WiFi Socket is here.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).