$16.99 – 2x Tail caps, 1x Wrench, 1x Astrolux SM10 Smart Braking Taillight, 1x User Manual, 1x USB Cable usb.
I have checked all old coupons and price is $16.99 for Astrolux SM10 Smart Brake Sensing Bicycle Taillight (in Banggood). Price history, coupons and price alert are available on this page. Best price?
Latest coupon and price update (UTC):
Banggood ($16.99)
Banggood warehouse is located in China. As you can see I didn’t find any active coupon for this product right now… Isn’t it too expensive? It looks like it’s a good price (lower than average ($37.73)).
Link: Banggood product page
Price: $16.99
Additional Banggood coupons: first page and second page
Old coupons (from the oldest to the newest): BGc65dd2, FIN19948, BGOutlight10, F72142, BGfb4452, FIN84849, BGdfc2b0, BG409a6d, BGFEU29, BGdanOFF202, BG74bbfc, BG566529, BG589b2e, BG2f1b5a, BG899c07, BGSCHOOL8OFF, BGCYCLE5
(you can check these old coupons out, but these probably won’t work)
Other warehouses/versions
This item is available in 1 another warehouse/version!
1. China – Astrolux SL01 Front Bike Flashlight ($16.99)
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
Do you need price history chart (for all/most countries) for Astrolux SM10 Smart Brake Sensing Bicycle Taillight? There we go. The lowest price was: $12.99.
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)).