Just check coupons out (with price alert and history). Best price?
LED Luminus SST-40-W LED, Impact Resistance 1 m, Peak Beam Intensity 21600 cd, Peak Beam Distance 321 yards, IP Rating IP68 – 2m submersible, Weight 2.46oz, Dimensions L-5.17″xW-1″xH-1″, Maximum Brightness 1800 lumen
Aliexpress
There’re some similar (or not) items on Aliexpress
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. ($78.12): 00c906
you should apply the coupon in your cart after clicking “Proceed to checkout”. Click to copy code and open shop.
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k and https://couponsfromchina.com/short/5cd
Old coupons (from the oldest to the newest): BG10OFFAFF, BGflashlight, BG10OFFAFF1, BANGGOODSD, BGTorch4
(you can check these old coupons out, but these probably won’t work)
Price history and price alert
Here is price history (for all/most countries) for NITECORE MH10S Flashlight SST-40-W.
Price records source(s): 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)).