Groupon offers the Mota 2,400mAh Battery Case for Apple iPhone 5/5S in four colors for $34.99 with free shipping. That's $5 under our mention from February and the lowest total price we've seen for this battery case. (It's a current low by $7.) This low-profile case features a built-in 2,400mAh battery, which is purported to nearly double the life of the phone.