Aliexpress
Here are coupons that you can use.
Latest coupon and price update (UTC):
Banggood
Banggood warehouse is located in China. There is one great coupon!
Link: Banggood product page
Coupon (691.83 USD): BG589b2e
(CouponsFromChina.com tip: coupon code has to be applied in shop’s 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): BG449e95, BGVDGA07, BG717000, BGe9d232
(these coupons are old, so probably won’t work)
Price history and price alert
Here is price history (for all/most countries) for GPD XP Plus Dimensity 1200 6/256GB Game Console.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).