JustCase via Amazon offers Amazon Prime members the JustCase KickStand Case for iPhone 4 / 4S in Gray for $7.95 with free shipping. (It's also available in Black for $8.45.) (Non-members can spend $25 or more to qualify for free shipping; otherwise, shipping costs $5.10.) That's $12 off and the lowest total price we could find. It comes with two screen protectors.

Also available for Prime members is the JustCase Ladder Case for iPhone 4 / 4S in White for $5.95 or Black for $6.45, both with free shipping. (Non-members can spend $25 or more to qualify for free shipping; otherwise, shipping costs $5.10.) That's $9 off and another low. It comes with two screen protectors.

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 that currently there's a waitlist for Amazon Mom.)