There are many questions to be asked before offering specific advice, so here is some general advice.
Use a platform such as wordpress or drupal. These are robust open source CMS's which are easy to deploy, configure and secure. They are well supported with addins and themes as well. You will need an ecommerce module and there are good ones for both platforms.
Depending on how you are integrating, a CMS application with ecommerce built in might be a better idea. For example, my gallery has integrated ecommerce which works very well. This takes care of security for the financial transaction (SSL).
Blog Tool, Publishing Platform, and CMS ? WordPress
7 Best Free WordPress Ecommerce Plug-ins You Must Use
Drupal - Open Source CMS | Drupal.org
Resource Guide: Building an eCommerce Website | Drupal.orgPersonally I prefer wordpress but its a ford/holden kind of deal. Both have advocates and detractors. You need to check it out for yourself and work out which way is going to work best for you.
Example of ecommerce integrated in wordpress via nextgen gallery:
Ecommerce Demo | NextGEN GalleryLet me know if you want to talk about your plans more specifically.