Today only, JustDeals offers the Incipio EDGE Slider Case for iPhone 4 or 4S in Purple (pictured) or Blue for 77 cents plus $5 for shipping. That's the lowest total price we could find in either color by $2, outside of the price below, although we saw it for a buck less last month. This polycarbonate case features a 2-piece sliding shell and is dent-, scratch-, and impact-resistant.

A close price: All4Cellular offers it in purple for $3.95 plus $2 for shipping.