All4Cellular offers the SaFPWR Milano Rechargeable Smart Battery Case for iPhone 4 and 4S in four colors for $79.95. Coupon code "A4C10" cuts it to $71.95. With $2 for shipping, that's $12 under our January mention and the lowest total price we could find by $23. This case purports to double the battery life for an iPhone 4 or 4S. Deal ends April 2.