Venture-Electronics via Amazon offers Amazon Prime members this StudBox 3-in-1 Case for iPhone 4 / 4S in seven colors (Black/Burgundy pictured) for $14.99. Coupon code "IPHONE40" drops it to $8.99. With free shipping, that's $6 off and the lowest total price we could find. (Non-members can spend $25 or more to qualify for free shipping; otherwise, shipping costs $5.08.) This case features a silicone interior and polycarbonate exterior.

Note: To get this price be sure to select the cases that are fulfilled by Amazon; it's available in seven additional colors directly from the seller but with a $2.49 shipping charge.

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 there is currently a wait list for the Amazon Mom program.)