Aliexpress
Here are coupons that you can use.
Other warehouses/versions
This item is available in 1 another warehouse/version!
1. China – SONOFF DUALR3 Dual Relay Module Switch (20.78 USD)
Latest coupon and price update (UTC):
Banggood
Banggood warehouse is located in Europe 
. There are no active coupons for this product, but the price is pretty low isn’t it? I can’t tell you if this price is good – not enough records in my database, so I won’t judge.
Link: Banggood product page
Price: -3 USD
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!
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k
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
(sometimes old coupons work, so you can check them out (this site checks them on every price update))
Other warehouses/versions
This item is available in 1 another warehouse/version!
1. China – SONOFF DUALR3 Dual Relay Module Switch (20.78 USD)
Price history and price alert
Well, you won’t see price history chart, coz we have only 1 database record for this item (and price was 12.99 USD).
You can set price alert (for Banggood).