6.21 inch, MIUI 10, Snapdragon 845 Octa Core 2.8GHz, 6GB RAM, 256GB ROM, Fingerprint Sensor, 3400mAh Built-in.
Price history, coupons and price alert are available on this page. Let’s see what best price is ATM.
Aliexpress
I could not find it on Aliexpress. Click here to search by yourself.
Here are coupons that you can use.
Latest coupon and price update (UTC):
Banggood
Banggood warehouse is located in Europe. There are no active coupons for this product, but the price is pretty low isn’t it?
Link: Banggood product page
Price: $-3
It looks like this item is out of stock in Banggood. If you found it then please send me the link. I will replace it.
Click here to search on Banggood!
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k and https://couponsfromchina.com/short/i1u
Old coupons (from the oldest to the newest): 8BGM86256, 8BGM86257, 8BGM8625EU, 8BGM8626, 9BGM8256, 10BGM8256, 11BGM8256
(I don’t think these’re gonna work, but you can try ’em out anyway)
Other warehouses/versions
This item is available in 2 another warehouse/versions!
1. Europe – Xiaomi Mi8 6/256GB Black [EU/ES] ($-3)
2. Hong Kong – Xiaomi Mi8 6/256GB Blue ($-3)
Price history and price alert
Price history (for all/most countries) for Xiaomi Mi8 6/256GB Gold is here. The lowest price was: $284.99.
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)).