Controlled lines: 1, Operating Temperature: -20ºC-70ºC, Wireless Standard: 802.11 b/g/n, Transmission mode: Wi-Fi communication, Voltage Input: DC 5V, Enclosure Material: Fire-retardant ABS, APP Platform: free eWeLink for Android / iOS, Working Modes: APP/Voice/LAN Control, Humidity: 5%-90%RH / Non-condensing.
Check coupons or create price alert down below. 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 price update (UTC time):
Banggood
Banggood warehouse is located in China. I don’t think there is an active coupon right now – at least in my database.
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): 8Couponsde, 2203ActiesNL, BG00c906, BG589b2e
(you can check these old coupons out, but these probably won’t work)
Price history and price alert
Price history (for all/most countries) for SONOFF RE5V1C Relay Module 5V WiFi DIY Switch is here. The lowest price was: $6.43.
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)).