Amazon.com currently has a deal on the Elka® 2800mAh Li-ion Spare Replacement Battery for Samsung Galaxy S5 listed at $7.99 (Re. Price $19.99). Good for AT&T, Verizon, Sprint, and T-Mobile.
Plus when you use code 59UOR7JD you save an additional $3.00 at checkout bringing the price down $4.99! This item qualifies for FREE Standard Shipping with a purchase of $35 or more and is Amazon Prime Eligible and you can get it in a little as 2-days!