According to my DB the lowest price is 10.99 USD for 3-in-1 4000W Wall Socket (in Banggood). Price history, coupons and price alert are available on this page. What is best price?
Latest coupon and price update (UTC):
Banggood (10.99 USD)
Banggood warehouse is located in China. Too bad there’s no coupon right now in Banggood. But wait a sec… Is it a good price? Wow! That’s the lowest price in CouponsFromChina database!
Link: Banggood product page
Price: 10.99 USD
10.99 USD – This is the best price ever noted in my database!
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k
Old coupons (from the oldest to the newest): BG589b2e
(I don’t think these’re gonna work, but you can try ’em out anyway)
Aliexpress
Click here… to search for TESSAN TS-611-DE 3-in-1 4000W Wall Socket Extender on Aliexpress
Here are coupons that you can use.
Price history and price alert
Here is price history (for all/most countries) for TESSAN TS-611-DE 3-in-1 4000W Wall Socket Extender.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).