Aliexpress
Here are coupons that you can use.
Latest coupon and price update (UTC):
Banggood
Banggood warehouse is located in Hong Kong. I have no active coupons for you right now.
Link: Banggood product page
Price: -3 USD
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
Old coupons (from the oldest to the newest): pROMo8cuPoN, BGaa8ec1, hoNEYbGdeAlS, BG535584, BGJUNEGSG9, BG89eec5, BGJPMNCW04, Cuponation9, 9OFFSUMMER, BGe3555d, BG8OFFCOUPON, TTBLACK5, BGa04079, BGe7ea68, BG97db4d, BG295f4e
(these coupons are old, so probably won’t work)
Price history and price alert
Here is price history (for all/most countries) for CHUWI RzBox 5800H Mini PC 16/512GB BT5.2.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).