Aliexpress
Click here… to search for Huawei Mate 20 6/64GB Black on Aliexpress
Here are coupons that you can use.
Latest coupon code price check (UTC time):
Banggood
Banggood warehouse is located in China. I found coupon for you. Check this out.
Link: Banggood product page
Coupon (789.45 USD): Email5
(CouponsFromChina.com tip: just apply this code in your cart after clicking “Proceed to checkout”. Click to copy code and open shop)
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k
Old coupons (from the oldest to the newest): 11BGC1, 11BG2064, affiliate6, aff7off, bgssaff9, od7off, BGaDmITAd, 7bcdf9, BGBFAFF2019, BGCITYADS2019, BGMPB2020
(these codes were not working in latest coupon update, but you can check them out anyway)
Price history and price alert
Here is price history (for all/most countries) for Huawei Mate 20 6/64GB Black.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).