Just check coupons out (with price alert and history). Let’s see what best price is ATM.
Aliexpress
There’re some similar (or not) items on Aliexpress
Click here to search by yourself. Here are coupons that you can use.
Latest price update (UTC time):
Size 9.5x48mm, Weight 16.8g, Brand IPRee®, Material Titanium alloy
Banggood
Banggood warehouse is located in China. I am tired of searching coupons, but I found one for you…
Link: Banggood product page
1. ($14.65): BG589b2e
put item in your cart and apply coupon code there 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): Sports23q1, BGc28268, BG9dce6b
(there’s a little possibility that old coupon will work)
Price history and price alert
Price history (for all/most countries) for 120dB Whistle Titanium Alloy is here.
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)).