Jason's Cart is the easiest to use open source PHP ecommerce content management system available.
I built this program to allow my customers to make edits to their own websites without incurring a cost every time an update or change was needed. Many of my customers have hired me to build their complete ecommerce website from the ground up, including the content. I have been building websites for 15 years. I'll refund all of your money if you tell me you are not happy with my program, or my work, within the first 30 days.