Aliexpress
Here are coupons that you can use.
Latest price update (UTC time):
Banggood
Banggood warehouse is located in China.
Link: Banggood product page
Coupon (37.58 USD): 2203ActiesNL
Coupon (37.99 USD): BG00c906
(CouponsFromChina.com tip: just apply this code in your cart after clicking “Proceed to checkout”. Click to copy code and open shop)
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k
Old coupons (from the oldest to the newest): BGSONLED, AFfbG10, BGSONOFFL1, bgnewledstrip, bgsonofflight, bgledstripson, 502C6B, BGBFAFF2019, BGFFDR, BGCITYADS2019, BGAFF10OFF, BGLIGHT2020, BGTT10, bGhOnEy10, BGYEBWCN, BGdragonBoat, BGSS10%SW, BGSONOFF15, BGELIG0920, BGCuponation10, BG10OFFAFF, BGwhielabel, 13f142, BGLIG12, BG10OFFAFF1, 00c906, ADMITAD2212, 2022ACTIESNL, Terence, BGLED2203, MVC8SPRING, 8BGwbg2204
(these codes were not working in latest coupon update, but you can check them out anyway)
Price history and price alert
Do you need price history chart (for all/most countries) for SONOFF L1 5m Smart WiFi RGB LED Strip? There we go.
Price records source(s): Gearbest, Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).