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 (25.59 USD): BGSM30%
Coupon (26.23 USD): BG1128
(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): bcnlxk, AC18, 1830Q, CMB1, BG30Q, BGF1111, fInbG2020, BGff2020
(these codes were not working in latest coupon update, but you can check them out anyway)
Price history and price alert
Price history (for all/most countries) for 4x Samsung INR18650-30Q 3000mAh Button Top Battery With Box is here.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).