Aliexpress
Here are coupons that you can use.
Latest coupon code price check (UTC time):
Banggood
Banggood warehouse is located in China. I am tired of searching coupons, but I found one for you…
Link: Banggood product page
Coupon (214.99 USD): 7d18f7
(CouponsFromChina.com tip: apply it 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): BGCHT12, Email5, bGhOnEy10, BGARTM, BGmART, BGT12AD, bgshOOp10
(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 T12 Mini PC AMD A4-7210 8/128GB is here.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).