AnkerDirect via Amazon offers its Anker iPhone 6 Ultra Slim Battery Case, model no. AK-A1405011, for $59.99. Coupon code "AKSLIMIP" cuts it to $29.99. With free shipping, that's $30 under list and the lowest total price we could find. This MFI-certified case features a 2,850mAh battery adding up to 19 hours of talktime.