Aliexpress
Click here… to search for Nicron NRB-L750 750mAh/3.7V 14500 Protected Battery on Aliexpress
Here are coupons that you can use.
Latest coupon code price check (UTC time):
Banggood
Banggood warehouse is located in China. You can get coupon down below.
Link: Banggood product page
Coupon (15.83 USD): BG10OFFAFF1
(CouponsFromChina.com tip: apply code in your basket (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): 903328, linepayflt, EYBG, BGTORCH, 502C6B, BGBFCR41, BGAFF10OFF, BgoFErTaSchInA10, 4BLF, BgcLuBofErtA10, BGFLS15, BGCuponation10, BGHONEY2110, BG10OFFAFF, BGwhielabel, BGFLBA
(sometimes old coupons work, so you can check them out (this site checks them on every price update))
Price history and price alert
Here is price history (for all/most countries) for Nicron NRB-L750 750mAh/3.7V 14500 Protected Battery.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).