(Note: If it is used for LED or energy saving bulb /the power load should be less than 100W), RF Frequency: 433MHz., Working voltage: 220V AC, Type: 1/2/3 Gang, Load Power: 3-300W/gang, Color: White /Black /Gold, RF Standard Code: 1527, Wireless type: Wi-Fi 2.4GHz.
Basically copy coupon, view price history or create e-mail price alert. Let’s see what best price is ATM.
Aliexpress
There’re some similar (or not) items on Aliexpress
You can use link bot to get even lower price:
Click here to search by yourself. Here are coupons that you can use.
Latest coupon code price check (UTC time):
Banggood
Banggood warehouse is located in China. So I have checked for active coupons (all category coupons and old ones), but there was no working coupon in Banggood.
Link: Banggood product page
Price: $-3
It looks like this item is out of stock in Banggood. If you found it then please send me the link. I will replace it.
Click here to search on Banggood!
Additional Banggood coupons: first page and second page
Old coupons (from the oldest to the newest): BG1735414, 6GSGIT, ADMITAD2212, BGSmart6, MVC8SPRING, 8BGwbg2204, tRaDetRaCKeR, 8wEbgaInS5, pROMo8cuPoN, BG8ReviTrage, Cuponation9
(these codes were not working in latest coupon update, but you can check them out anyway)
Other warehouses/versions
This item is available in 1 another warehouse/version!
1. Europe – Moeshouse 220V WiFi Smart Light Switch RF433 [EU] ($-3)
Price history and price alert
Price history (for all/most countries) for Moeshouse 220V WiFi Smart Light Switch RF433 is here. The lowest price was: $15.25.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood and Aliexpress (only if product name will be the same as on Banggood and I will post it on social media though, so it’s more like Banggood price alert)).
. I couldn’t find any coupon for this product on latest product update. There’s only 1 record in my database, so I have no idea if the price is OK.