BuyDig offers the uNu Power DX 2,300mAh Rechargeable Battery Case for iPhone 5 and 5S in Matte Black, model no. DX-05-2300B, for $79. Coupon code "IPHONEJUICE" cuts the price to $44. With free shipping, that's a buck under our mention from three days ago and the lowest total price we could find by $11. It purports to provide an additional 10 hours of talk time or eight hours of additional web-browsing