There are numerous great E-commerce solutions available for wordpress users and many of them are FREE. In this article I am trying to list the most effective ones which are compatible with the latest version of the wordpress. For the Ebay users, I recommend PHPbay Free edition which will automatically search products and display on your posts, for Amazon I recommend WP-amazon auto poster which will create up to 16 posts automatically based on your keyword. Reviewazon is an upcoming plugin but is not free. If you are selling your own products, use Eshop or WP-ecommerce. You can use the WordPress Simple Paypal Shopping Cart to create shopping pages that can accept paypal payments.