Aliexpress
Click here… to search for Jumper EZbook S4 4/128GB Laptop on Aliexpress
Here are coupons that you can use.
Latest coupon code price check (UTC time):
Banggood
Banggood warehouse is located in China. There is one coupon right now! Check this out.
Link: Banggood product page
Coupon (289.05 USD): Wholesale20
(CouponsFromChina.com tip: coupon code has to be applied in shop’s 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): 1J1NBG1, 1225CAR, CES4128, TECH8%
(you can check these old coupons out, but these probably won’t work)
Price history and price alert
Here is price history (for all/most countries) for Jumper EZbook S4 4/128GB Laptop.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).