Aliexpress
Here are coupons that you can use.
Latest coupon code price check (UTC time):
Banggood
Banggood warehouse is located in China.
Link: Banggood product page
Coupon (40.99 USD): BGFW21
Coupon (46.98 USD): cbrIDgTec
Coupon (48.15 USD): fInbG2020
Coupon (49.91 USD): BGff2020
(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): BGF1111, BGTORCH, BGBFCR41
(I don’t think these’re gonna work, but you can try ’em out anyway)
Price history and price alert
Here is price history (for all/most countries) for LUMINTOP FW21 3x XPL HI/SST20 Flashlight FW3A 21700.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).