According to my DB the lowest price is $14.99 for SONOFF DUALR3 Dual Relay Module Switch (in Banggood). You can create price alert here, copy coupons and view price history. You probably want to know what is the best price?
Latest coupon code price check (UTC time):
Enclosure Material: Fire-retardant ABS V0, Security Mechanism: WPA-PSK/WPA2-PSK, Gang: 2, Color: White, Max Current: 15A(total) /10A(1 gang), Humidity: 5%-95%RH / Non-condensing, Frequency: 802.11 b/g/n, Operating Temperature: -10ºC-40ºC, Product Dimensions: 54*49*24mm, Power Supply: 100-240V AC, Max Power: 3300W(total) / 2200W(1 gang)
Banggood ($14.99)
Banggood warehouse is located in China. CouponsFromChina software could not find any coupon for this product in Banggood. Is it a reasonable price for this item? This price is higher than average price ($11.94) for this item.
Link: Banggood product page
Price: $14.99
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k and https://couponsfromchina.com/short/5cd
Old coupons (from the oldest to the newest): BGDUALR3, BGDUALR313, 13f142, BG36c08a, BGee1672, BG619c1a, 6GSGIT, ADMITAD2212, BGSmart6, 8Couponsde, MVC8SPRING, 8wEbgaInS5, pROMo8cuPoN, BGJUNEGSG9, BG15Sonoff, BG8ReviTrage, Cuponation9, 9OFFSUMMER, BG32140d
(system checks these coupons on every price check (like once per 24 hours), but you can check them out anyway)
Other warehouses/versions
This item is available in 1 another warehouse/version!
1. Europe – SONOFF DUALR3 Dual Relay Module Switch [EU] ($-3)
Aliexpress
There’re some similar (or not) items on Aliexpress
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 DUALR3 Dual Relay Module Switch.
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)).
. CouponsFromChina software could not find any coupon for this product in Banggood. Sorry, but there’s no price history in my database.