Aliexpress
Click here… to search for Klarus ST15 Flashlight on Aliexpress
Here are coupons that you can use.
Latest coupon code price check (UTC time):
Banggood
Banggood warehouse is located in China. Only one coupon available!
Link: Banggood product page
Coupon (32.16 USD): 2017FNL
(CouponsFromChina.com tip: coupon code has to be applied in shop’s 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): 44190c
(I don’t think these’re gonna work, but you can try ’em out anyway)
Price history and price alert
Check out price history chart (for all/most countries) for Klarus ST15 Flashlight.
Price records source(s): Gearbest, Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).