CTCStore offers Amazon Prime members the Acase Superleggera Case for Apple iPhone 4 / 4S in Black for $12.90. Coupon code "PEWWJ9UD" cuts it to $5.95. With free shipping, that's tied with last month's mention and $14 less than buying it direct from Acase. (Non-members can spend $25 or more to qualify for free shipping; otherwise, shipping costs $5.05.) This polycarbonate and silicone case protects against dust and scratches. Coupon expires May 6.

Amazon Prime membership is $79 per year; however, Prime is free for college students for six months, and free for parents and caregivers for three months.