Aliexpress
Here are coupons that you can use.
Latest coupon code price check (UTC time):
Banggood
Banggood warehouse is located in China. Too bad there’s no coupon right now in Banggood.
Link: Banggood product page
Price: -3 USD
It looks like this item is out of stock in Banggood. If you found it then please send me the link. I will replace it.
Click here to search on Banggood!
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k
Old coupons (from the oldest to the newest): 76351b, fc91da, 3b5d77, b1652d, BG203595, aff7off, BG6d8f77, BGb05428, BG362f4b, BG7dd91f
(probably won’t work, but you can try them out)
Price history and price alert
Here is price history (for all/most countries) for Cube Mix Plus 4/128GB Tablet.
Price records source(s): Gearbest, Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).