For its newsletter subscribers only, EverydaySource offers this Rubber-coated Snap-on Case for iPhone 4 / 4S 3-Pack for $14.99. Coupon code "S0221NBEQ" cuts it to $6.29 and bags free shipping. That's $2.10 per case and the lowest total price we could find for this quantity by $4. This includes a red, black, and light blue case with a white-dotted rear.