Aliexpress
Here are coupons that you can use.
Other warehouses/versions
This item is available in 1 another warehouse/version!
1. Europe – 4x Astrolux C2150 5000mAh 3C 3.7V 21700 Battery 15A [EU] (-3 USD)
Latest coupon code price check (UTC time):
Banggood
Banggood warehouse is located in China.
Link: Banggood product page
Coupon (39.60 USD): BG8Alerabat
Coupon (39.60 USD): BGLED07
(CouponsFromChina.com tip: you should apply the coupon 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): BGABA, BGAST25, BGDEALS06, BGAFF10OFF, BGCuponation10, 4BLF, BG10OFFAFF, cbrIDgTec, BG10OFFAFF1, BGFLBA, BANGGOODSD, BGTorch4, 00c906, BGtorch2, BGtorch3, BGtorch7, BGAlerabatI, BGtorch9, BG3f1f8e, BGOutlight10
(I don’t think these’re gonna work, but you can try ’em out anyway)
Other warehouses/versions
This item is available in 1 another warehouse/version!
1. Europe – 4x Astrolux C2150 5000mAh 3C 3.7V 21700 Battery 15A [EU] (-3 USD)
Price history and price alert
Price history (for all/most countries) for 4x Astrolux C2150 5000mAh 3C 3.7V 21700 Battery 15A is here.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).