Aliexpress
Here are coupons that you can use.
Latest coupon code price check (UTC time):
Banggood
Banggood warehouse is located in China. I found coupon for you. Check this out.
Link: Banggood product page
Coupon (367.99 USD): hoNEYbGdeAlS
(CouponsFromChina.com tip: just apply this code 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): BG655b23, Terence, BG6e5fec, BG778bec, CouponsdePC, BG547aa8, BG4b56fd, BGd95436, BG478765, BG8ec0f7, BG3267ae, pROMo8cuPoN, BGd1aa48
(there’s a little possibility that old coupon will work)
Price history and price alert
Do you need price history chart (for all/most countries) for T-Bao TBOOK MN22 Mini PC 3150U 8/128GB? There we go.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).