Aliexpress
Here are coupons that you can use.
Latest coupon code price check (UTC time):
Banggood
Banggood warehouse is located in China.
Link: Banggood product page
Coupon (259.99 USD): Wholesale20
Coupon (259.99 USD): BGTF6A
(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): 1B0G3F16, 1B1G1LAP1, 12F6HTD, 12F6H25, 27F6BG, BG37F6, F637BG, TECH8%, F63D29, f6gizchina, BGAPF6, bgf6hot, F6BG705, BGF6510, BGTCF6, BGF624, BGXM3D13, BGJL3D16, BGJL6888, BGTEC9705, BGTECF6705, BGTECF67051, BGTEC1
(probably won’t work, but you can try them out)
Price history and price alert
Check out price history chart (for all/most countries) for Teclast F6 6/128GB Laptop.
Price records source(s): Gearbest, Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).