Aliexpress
Click here… to search for Xiaomi Black Shark 2 Pro 8/128GB on Aliexpress
Here are coupons that you can use.
Latest coupon code price check (UTC time):
Banggood
Banggood warehouse is located in Hong Kong. Too bad there’s no coupon right now in Banggood.
Link: Banggood product page
Price: -3 USD
It looks like this item is out of stock in Banggood. If you found it then please send me the link. I will replace it.
Click here to search on Banggood!
Old coupons (from the oldest to the newest): BG5BS2P, Email5
(I don’t think these’re gonna work, but you can try ’em out anyway)
Price history and price alert
Check out price history chart (for all/most countries) for Xiaomi Black Shark 2 Pro 8/128GB.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).