Aliexpress
Here are coupons that you can use.
Latest price update (UTC time):
Banggood
Banggood warehouse is located in China. 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): BG8bbb9e, BG69ea15, 7bcdf9, BG67da35, BGUM700256G, BG7d5ae9, BGHU1046, 6GSGIT, 00c906, BGe82555, BGef96eb, BG0cce2b, BG808646, BG3f4bee, Kortings10, 2022ACTIESNL, BG1c5777, BG01e1e2, BG0202ac, BG2b6f41, BGac13ff
(these codes were not working in latest coupon update, but you can check them out anyway)
Price history and price alert
Price history (for all/most countries) for Minisforum UM700 3750H 8/256GB Mini PC is here.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).