Aliexpress
Here are coupons that you can use.
Latest price update (UTC time):
Banggood
Banggood warehouse is located in China.
Link: Banggood product page
Coupon (413.59 USD): affiliate6
Coupon (419.99 USD): Wholesale20
(CouponsFromChina.com tip: put item in your cart and apply coupon code there 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): 10JEZ3P, 1B1G1LAP1, 1B2G706, 1B2G70618, 1B2G2406, 1B2G2426, 19BGJ3P, 19BGEK3, 408BG767, aff7off
(these codes were not working in latest coupon update, but you can check them out anyway)
Price history and price alert
Here is price history (for all/most countries) for Jumper EZbook 3 Plus 8/128GB Notebook.
Price records source(s): Gearbest, Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).