Aliexpress
Here are coupons that you can use.
Latest coupon and price update (UTC):
Banggood
Banggood warehouse is located in China.
Link: Banggood product page
Coupon (15.01 USD): Cuponation9
Coupon (15.50 USD): BG00c906
(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): BGJUNEGSG9, 9OFFSUMMER
(probably won’t work, but you can try them out)
Price history and price alert
Do you need price history chart (for all/most countries) for Gideatech 12 Digits Display Calculator with Writing Tablet? There we go.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).