Aliexpress
Here are coupons that you can use.
Latest coupon code price check (UTC time):
Banggood
Banggood warehouse is located in Hong Kong. There are no coupons available at this moment 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): 2022ACTIESNL, BGb3125d, BGAlerabat1, BG9ddd39, BGf4f231, Terence, BGd52a97, Tabby20, BGb1def9, BGba9e7e, 2203ActiesNL, BGd30069, CouponsdePC, tRaDetRaCKeR, BG01a58b, 8wEbgaInS5, BG6a8a68, pROMo8cuPoN, BGe74cd7, BGJUNEGSG9, BGJPMNBK20, Cuponation9, BGa9301c, BgGoodie9
(these codes were not working in latest coupon update, but you can check them out anyway)
Price history and price alert
Here is price history (for all/most countries) for Beelink SER4 4800U 32/500GB Mini PC.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).