Aliexpress
There’re some similar items on Aliexpress in my database. There may be some other items though.
| Image | Product (link) | Price | Coupons |
|---|---|---|---|
 |
2x LiitoKala NCR18650B 3.7V 3400mAh 18650 Battery | 6.49 USD | – |
More on Aliexpress… Here are coupons that you can use.
Latest coupon and price update (UTC):
Banggood
Banggood warehouse is located in China. There is one coupon available! Pretty cool, huh?
Link: Banggood product page
Coupon (18.27 USD): BANGGOODSD
(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): BGMTQ, linepayflt, CMB3, BGTORCH, fInbG2020, BGff2020, BGCuponation10, BG10OFFAFF, BGwhielabel, 4BLF, BG10OFFAFF1, 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 2x LiitoKala Lii-40A 21700 4000mah Battery.
Price records source(s): Gearbest, Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).