3.7V 455mAh, 36 hours (Lights on), Standby 180 days.
Check coupons or create price alert down below. What is the 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 code price check (UTC time):
Banggood
Banggood warehouse is located in China. I am tired of searching coupons, but I found one for you…
Link: Banggood product page
1. ($56.71): 935bc1
put item in your cart and apply coupon code there after clicking “Proceed to checkout”. Click to copy code and open shop.
Additional Banggood coupons: first page and second page
Old coupons (from the oldest to the newest): a9e2f1, AlibuySH50, 0a4f61, Alibuy91224, LSTR93
(sometimes old coupons work, so you can check them out (this site checks them on every price update))
Other warehouses/versions
This item is available in 1 another warehouse/version!
1. China – Xiaomi Youpin Smart4u Bicycle Helmet Black ($-3)
Price history and price alert
Price history (for all/most countries) for XIAOMI Smart4u SH50 Cycling Helmet White is here. The lowest price was: $35.99.
Price records source(s): Gearbest, 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)).