Color Black, Waterproof Storm-proof, Volume 110-120dB, Weight 37g, Size 90mmx 45mmx 40mm, Brand ZTTO, Sound Three kinds of sound, Material ABS+PC, Name Bicycle Electronic Bell.
Just check coupons out (with price alert and history). 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 price update (UTC time):
Banggood
Banggood warehouse is located in China. I found coupon for you. Check this out.
Link: Banggood product page
1. ($11.87): BGCYCLE5
apply it in your cart 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): BG9d0e1b, BG075570, BGec1575, BG1ff31e, BG03b891, 8Couponsde, MVC8SPRING, BGac2e1e, BGef15dc, 8BGwbg2204, tRaDetRaCKeR, BG3b6337, BGfc4568, Cuponation9, BG00c906, BG589b2e, BG882649
(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 ZTTO Waterproof 120db Bicycle Electric Bell Horn. The lowest price was: $6.99.
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)).