CTCStore offers Amazon Prime members the Acase Superleggera Case for Apple iPhone 4 / 4S in Black for $4.95 with free shipping. That's tied with our mention from a month ago and the lowest total price we could find by $8. (Non-members can spend $25 or more to qualify for free shipping; otherwise, shipping costs $5.01.)

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. (Note there is currently a wait list for Amazon Mom.)