Size: 125.4mm * 24mm, Switch: tail switch, LED: Nichia NCSU276A 365nm, Waterproof: IPX6, Mode: single high mode.
Basically copy coupon, view price history or create e-mail price alert. What is best price?
Aliexpress
There’re some similar (or not) items on Aliexpress
You can use link bot to get even lower price:
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.
Link: Banggood product page
1. ($16.03): fInbG2020
2. ($16.62): BGff2020
3. ($17.20): BGTORCH
4. ($17.20): BGSF
put item in your cart and apply coupon code there after clicking “Proceed to checkout”. Click to copy code and open shop.
Additional Banggood coupons: first page and second page
Old coupons (from the oldest to the newest): 502C6B, e2bcea, linepayflt, EYBG, BGBSPX, BGBFCR41
(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 Sofirn SF32UV Nichia 365UV UV Flashlight. The lowest price was: $13.29.
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)).