Aliexpress
Here are coupons that you can use.
Latest coupon code price check (UTC time):
Banggood
Banggood warehouse is located in Hong Kong. There is one great coupon!
Link: Banggood product page
Coupon (785.06 USD): CouponsdePC
(CouponsFromChina.com tip: this code has to be applied 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): BG597549, 2022ACTIESNL, BG5fa3d2, Tabby20, BG36c010, BGdb5854
(you can check these old coupons out, but these probably won’t work)
Price history and price alert
Check out price history chart (for all/most countries) for Beelink GT-R PRO 3550H Vega 8 16/512GB 1TB Mini PC.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).