Amazon offers its Amazon Prime members the Lexar 8GB SDHC Class 6 Secure Digital High-Capacity Card (pictured), model no. LSD8GBBE100, for $12.49 $10.99 with free shipping. (Non-members can spend $25 or more to qualify for free shipping; otherwise, shipping costs $5.58.) That's $1.37/GB, $5 under April's mention, and the lowest total price we could find by $4.

Also available for Amazon Prime members is the Lexar 4GB SDHC Class 6 Secure Digital High-Capacity Card, model no. LSD4GBBE100, for $8.49 $7.99 with free shipping. That's $2/GB and another price low by $3.

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