Just check coupons out (with price alert and history). You probably want to know what is the best price?
Aliexpress
There’re some similar (or not) items on Aliexpress
Click here to search by yourself. Here are coupons that you can use.
Latest price update (UTC time):
3.7V 400mAh, Waterproof: IPX-4, Working Time: 3 – 5 days
Price history and price alert
Here is price history (for all/most countries) for K8 Portable GPRS GPS Locator [Fast-08].
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)).