On the 1 Februrary 2014 Meetup, Russ and Bobbi Sanderlin covered their take on selling products using WordPress. Their shopping cart of choice is WooCommerce, and they walked attendees through the use of this plugin, as well as free and paid extensions. They then juxtaposed this with using Gravity Forms to sell products.
From their topic notes:
We will cover the main plug-in of Woocommerce along with Gravity forms to offer variations of products. Gravity forms enables a better approach implementing products with the same options.