$27.42 – Nominal Capacity 2530mAh, Minimum Capacity 2500mAh, Name Astrolux® E1825 2500mAh 18A 18650 Battery, Internal Resitance Max 20mΩ, Operate Temperature / Discharge -20℃~60℃, Max Discharging Current 18A, Brand & Model Astrolux® E1825, Charging Cut-off Voltage 0.02C, Nominal Voltage 3.7v, Discharging Cut-off Voltage 3.00V, Storage Temperature -5℃~25℃, Net weight 44±2 g, Size / Length 65.1±0.30 mm, Operate Temperature / Charge 0℃~45℃, Charging Current 1.00C, Size / Diameter 18.5±0.30 mm.
According to my DB the lowest price is $27.42 for 4 pcs. Astrolux E1825 2500mAh 3.7V 18650 Battery 18A (in Banggood). You can create price alert here, copy coupons and view price history. Best price?
Latest coupon code price check (UTC time):
Banggood ($27.42)
Banggood warehouse is located in China. Is it cheap? Well, this price is higher than average price ($17.99) There is one great coupon!
Link: Banggood product page
Price without coupon: $28.86
1. ($27.42): BGTORCH10
put item in your cart and apply coupon code there after clicking “Proceed to checkout”. Click to copy code and open shop.
Additional Banggood coupons: first page and second page
Old coupons (from the oldest to the newest): BG4E1825, BGE1825, BGwhielabel, FIN1079, BG1825, 4BLF, BGA4E1825, BG10OFFAFF1, BGFLBA, BANGGOODSD, BGTorch4, BGASTB, BGdeals332, FIN5107, BGtorch2, BGAlerabatI, BGASTC, BGtorch9, BG8Alerabat, BGea3410, BGLED07, BGOutlight10, BGa15acb, FIN0410, BG589b2e, BGd57765
(there’s a little possibility that old coupon will work)
Other warehouses/versions
This item is available in 1 another warehouse/version!
1. Europe – 4 pcs. Astrolux E1825 2500mAh 3.7V 18650 Battery 18A [EU] ($-3)
Aliexpress
There’re some similar (or not) items on Aliexpress
You can use link bot to get even lower price:
Click here to search by yourself. Here are coupons that you can use.
Price history and price alert
Price history (for all/most countries) for 4 pcs. Astrolux E1825 2500mAh 3.7V 18650 Battery 18A is here. The lowest price was: $13.99.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood and Aliexpress (only if product name will be the same as on Banggood and I will post it on social media though, so it’s more like Banggood price alert)).