All4Cellular offers the Incipio EDGE Slider Case for iPhone 4 or 4S in Metallic Purple for $3.95. Coupon code "A4C2012" drops it to $3.48. With $2 for shipping, that's the lowest total price we could find by $5. This polycarbonate case features a 2-piece sliding shell and is dent-, scratch-, and impact-resistant. Deal ends December 16.