CTCStore offers Amazon Prime members the Acase Matte Screen Protector for iPhone 4 / 4S 3-Pack for $8.45. Coupon code "FVE8CHTD" drops it to $2.98. With free shipping, that's pennies under our mention from a week ago and the lowest total price we could find for a comparable set by $2, outside of the price below. (Non-members can spend $25 or more to qualify for free shipping; otherwise, shipping costs $5.03.) It includes three front screen protectors. Coupon expires February 2.

A close price: eForcity via Sears has a similar 3-pack for $3.15 with free shipping.

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.)