$4.99 – BENGGUO Bicycle Horn 120dB Bike Bell (Banggood, Aliexpress: BENGGUO Bicycle Horn 120dB High Sound Bike Bell Horn 5 Light Modes 200mAh Type-C Waterproof Electric Horn for Cycling – Black (the best price with coupon)).
I have just checked coupons. The lowest price I could get is $4.99 for BENGGUO Bicycle Horn 120dB Bike Bell (in Banggood). Just check coupons out (with price alert and history). Let’s see what best price is ATM.
Latest coupon and price update (UTC):
Banggood ($4.99)
Banggood warehouse is located in China. The question is – is it a good price? Actually this is the best price in history according to CouponsFromChina database! There is one great coupon!
Link: Banggood product page
Price without coupon: $7.99
1. ($4.99): BG01TYJ54
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 and https://couponsfromchina.com/short/feV
Old coupons (from the oldest to the newest): BGTY12M30, BG6e6399
(these codes were not working in latest coupon update, but you can check them out anyway)
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.
Price history and price alert
Here is price history (for all/most countries) for BENGGUO Bicycle Horn 120dB Bike Bell. The lowest price was: $4.99.
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)).