$18.99 – Max. Load: 10A/2200W/Gang 16A/3500W/Total, Operating Temperature(recommended): -10ºC-40ºC(14°F-104°F), Enclosure Material: PC V0, Non-condensing, Dimension: 145*90*34 (mm), Operating Humidity: 5%-95%RH, Voltage Range: 100-240V AC 50/60Hz, Wireless Frequency: WiFi 2.4GHz, Wireless Standard: IEEE802.11 b/g/n 2.4GHz(2400M-2483.5M), Security Mechanism: WPA/WPA2, Gang: 4.
I have checked all old coupons and price is $18.99 for SONOFF 4CH R3 10A 2200W 4 Gang WiFi Smart Switch (in Banggood). Basically copy coupon, view price history or create e-mail price alert. What is the best price?
Latest price update (UTC time):
Banggood ($18.99)
Banggood warehouse is located in China. There are no coupons available at this moment in Banggood. I think you want to know if the price is good. My database says that it’s pretty good price, coz average is $19.32.
Link: Banggood product page
Price: $18.99
Additional Banggood coupons: first page and second page
Old coupons (from the oldest to the newest): BGSS10%SW, BGSONOFF15, BGSOFR3, BGSONOFFR3, BG4CHR3, BGSONOFF16, BGSTHO15, BGCuponation10, BGHONEY2110, BGSHOM15, 13f142, BGSHE15, BGa0c014, 6GSGIT, ADMITAD2212, BGSmart6, BGc7512a, MVC8SPRING, 8wEbgaInS5, pROMo8cuPoN, hoNEYbGdeAlS, BGARHS034, BGJUNEGSG9, BG15Sonoff, BG8ReviTrage, Cuponation9, BGHU2319, BG7c4c0f, BGGutscheine, BG8OFFCOUPON, BG1cc4fe
(I don’t think these’re gonna work, but you can try ’em out anyway)
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.
Price history and price alert
Check out price history chart (for all/most countries) for SONOFF 4CH R3 10A 2200W 4 Gang WiFi Smart Switch. The lowest price was: $17.99.
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)).