Aliexpress
Here are coupons that you can use.
Latest price update (UTC time):
Banggood
Banggood warehouse is located in Hong Kong. Only one coupon available!
Link: Banggood product page
Coupon (64.17 USD): 2203ActiesNL
(CouponsFromChina.com tip: this code has to be applied 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): Tabby20
(probably won’t work, but you can try them out)
Price history and price alert
Check out price history chart (for all/most countries) for DOOGEE X93 6.1 inch 2/16GB 4350mAh MT6580.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).