2 channels.
You can create price alert here, copy coupons and view price history. What is best price?
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 coupon and price update (UTC):
Banggood
Banggood warehouse is located in China. I found coupon for you. Check this out.
Link: Banggood product page
1. ($24.79): BGf2b910
just apply this code in your cart after clicking “Proceed to checkout”. Click to copy code and open shop.
Additional Banggood coupons: first page and second page
There were country-specific coupon codes published on Couponsfromchina social channels and price alerts. Coupon price may vary by country, because there’re different VAT rates, shipping cost etc. There is a chance that some latest coupons are still working:
Old coupons (from the oldest to the newest): e2bcea, 502C6B, 847fc3, elec, BGMINIT1, bGhOnEy10, BGSMOFF, BGSONOFFT1, 13f142, BGSONOFF15, BGELIG0920, BgcLuBofErtA10, BGSONOFF16, BGAFF10OFF, BGSTHO15, BGCuponation10, BGHONEY2110, BGSHOM15, BGSHE15, 6GSGIT, ADMITAD2212, BGSmart6, MVC8SPRING, BG15Sonoff, Cuponation9, BG8ReviTrage, BG597de7, BG12MAY2023F, BGdd54b4
(probably won’t work, but you can try them out)
Other warehouses/versions
This item is available in 3 another warehouse/versions!
1. China – SONOFF T1 3CH Wifi Smart Switch ($-3)
2. China – SONOFF T1 1CH Wifi Smart Switch ($-3)
3. Europe – SONOFF T1 2CH Wifi Smart Switch [EU] ($-3)
Price history and price alert
Do you need price history chart (for all/most countries) for SONOFF T1 2CH Wifi Smart Switch? There we go. The lowest price was: $12.03.
Price records source(s): Gearbest, 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)).