Aliexpress
Here are coupons that you can use.
Latest price update (UTC time):
Banggood
Banggood warehouse is located in Hong Kong. I’m afraid that there’s no working coupon in Banggood.
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): BGc7eb2c, BG3e80d2, BG875910, pROMo8cuPoN, BG08d90e, BG4e6ed3, BGJOETKS3H, Cuponation9, 9OFFSUMMER, BGa77cb6, BG70f0f1, BGTKMN15OFF, BGTKMN20OFF, BGadb6c0, BGd823d1, BG3650e6
(there’s a little possibility that old coupon will work)
Price history and price alert
Price history (for all/most countries) for TRIGKEY Speed S3 3750H RX Vega 10 Mini PC 8/256GB is here.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).