ATM you can buy Tuya 16A for 16.09 USD (in Banggood). Price history, coupons and price alert are available on this page. You probably want to know what is the best price?
Latest coupon code price check (UTC time):
Banggood (16.09 USD)
Banggood warehouse is located in China. As you can see I didn’t find any active coupon for this product right now… Is it expensive? Maybe there’re no more promotions for this item, because current price is higher than average (which is equal 12.99 USD)
Link: Banggood product page
Price: 16.09 USD
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k
Old coupons (from the oldest to the newest): BGbef792
(you can check these old coupons out, but these probably won’t work)
Aliexpress
There’re some similar items on Aliexpress in my database. There may be some other items though.
More on Aliexpress… Here are coupons that you can use.
Price history and price alert
Here is price history (for all/most countries) for Tuya 16A Smart WiFi Power Socket with USB.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).