Aliexpress
Here are coupons that you can use.
Latest coupon and price update (UTC):
Banggood
Banggood warehouse is located in China.
Link: Banggood product page
Coupon (7.00 USD): BGSM15
Coupon (7.41 USD): bGhOnEy10
(CouponsFromChina.com tip: apply it 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): affiliate6, aff7off, bgssaff9, BGaDmITAd, bgchinafest, BGCITYADS2019, bGpAnDacHeCk
(probably won’t work, but you can try them out)
Price history and price alert
Price history (for all/most countries) for Broadlink SC1 Smart Switch is here.
Price records source(s): Gearbest, Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).