5V/12V ESP8266 4 Channels WiFi Relay (Banggood, Aliexpress: 1x Relay module (the best price with coupon)).
You can create price alert here, copy coupons and view price history. Best price?
Aliexpress
There’re some similar (or not) items on Aliexpress
You can use link bot to get even lower price:
| Image | Product (link) | Price | Coupons |
|---|---|---|---|
 |
Internet of Things Smart Home Mobile APP Remote Control Switch 5V 12V 4 Channels WiFi Relay ESP8266 | $8.54 | – |
Click here to search by yourself. Here are coupons that you can use.
Latest price update (UTC time):
Banggood
Banggood warehouse is located in China. There is one coupon available! Pretty cool, huh?
Link: Banggood product page
1. ($9.39): BG00c906
apply it in your cart after clicking “Proceed to checkout”. Click to copy code and open shop.
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k and https://couponsfromchina.com/short/feV
Old coupons (from the oldest to the newest): 2203ActiesNL, BGJUNEGSG9, Cuponation9
(I don’t think these’re gonna work, but you can try ’em out anyway)
Price history and price alert
Price history (for all/most countries) for 5V/12V ESP8266 4 Channels WiFi Relay is here. The lowest price was: $9.09.
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)).