If you are searching for a shopping cart (eventually for The Best shopping cart ), zippycart.com offers you a very useful comparison tool. There are no open source carts listed here, but you can consider if one of these suits your needs.
Prices are starting from $19.99/month (plus one-time setup fee) and you cand compare the shopping cart look & feel, features like printable shipping labels, email marketing or mailing lists, coupon codes, wish lists, affiliate advertising tools, but also daily back-up and restore option, tech support, etc.
Here is …

Wordpress is becoming more & more flexible every day, no longer is it just a blogging platform. Now, by simply activating a plugin, you can transform your blog into a fully functional eCommerce store, ready to sell your products. Here is the list of best Wordpress eCommerce plugins, both free and paid:
1. WP-eCommerce (free) – the most popular eCommerce plugin, has been downloaded over 300,000 times so far. There’s a free version & a gold version, both also working with WP-MU. Main features: