You can create price alert here, copy coupons and view price 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 coupon code price check (UTC time):
5.0 inch, MIUI 8, Snapdragon 435, Octa Core 1.4GHz, 13.0MP Rear Camera, Fingerprint Scanner, 4100mAh Battery, 3GB RAM, 32GB ROM
Price history and price alert
Check out price history chart (for all/most countries) for Xiaomi Redmi 4X 3/32GB Global Gold [HK].
Price records source(s): Gearbest
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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)).