Aliexpress
Here are coupons that you can use.
Latest price update (UTC time):
Banggood
Banggood warehouse is located in Hong Kong.
Link: Banggood product page
Coupon (782.99 USD): CouponsdePC
Coupon (809.09 USD): Terence
Coupon (809.09 USD): 2203ActiesNL
(CouponsFromChina.com tip: you should apply the coupon 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): BGc1674e, BGJPRZ9H, BG90984c, 00c906, BGdfe871, BGb44039, BG4b30bb, BGIT1MN01, BGf08829, BGef96eb, Kortings10, 2022ACTIESNL, BGb143f1, BGAlerabat1, Tabby20
(there’s a little possibility that old coupon will work)
Price history and price alert
Price history (for all/most countries) for CHUWI RzBox Ryzen9 4900H RX Vega 8 Mini PC 16/512GB is here.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).