You can create price alert here, copy coupons and view price 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 coupon and price update (UTC):
APP is Available, Bluetooth 4.0 (Low Power Consumption), Three Pointers Watch, Calories Burnt, Luminous Watch, Camera Remote Control, Free of Charging, Activity Tracker: Step, 5 ATM professional waterproof and dustproof (you can wear it when washing hands. But hot water is not allowed.), Comfortable Silica Strap, Distance Tracking, One Key SOS, Calls and information reminder, Sport Data Record could be saved for 15 days (Circulation coverage), 12 months long endurance working time
Price history and price alert
Check out price history chart (for all/most countries) for NX05 Smart Watch.
Price records source(s): Gearbest
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)).