Amazon offers its Amazon Prime members Pixelmator for Mac for $16.13 with free shipping. (Non-members can spend $25 or more to get free shipping; otherwise it adds $4.98.) That's the lowest total price we could find by $28, although it was $4 less in our mention last year. This software lets you edit and retouch images with more than 20 tools. It features support for iPhoto and iSight.

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.