Aliexpress
Here are coupons that you can use.
Latest coupon code price check (UTC time):
Banggood
Banggood warehouse is located in Hong Kong.
Link: Banggood product page
Coupon (489.99 USD): BGBF20PU
Coupon (489.99 USD): BGCB20P
(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): BGEUTO20, BGBWEU412, BGTBEU20, BGEUTOB20, 6GSGIT, BGPREU20, BGTEU20P, BGRBF28, BGBFIT20P
(I don’t think these’re gonna work, but you can try ’em out anyway)
Price history and price alert
Price history (for all/most countries) for Teclast T.BOLT 20 Pro Laptop 15.6 inch i5-8259U 8/256GB is here.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).