If you would like to add ecommerce capabilities to your website, osCommerce is an ideal solution. Everything you need to get started in selling physical and digital goods over the internet, from the Catalog frontend that is presented to your customers, to the Administration Tool backend that completely handles your products, customers, orders, and online store data. Visit the DEMO
Agora is a great ecommerce solution for users with some HTML/Perl experience. Agora does not use a database to store product information. All product information is stored in flat files.
If you have a PayPal account, you can easily set up products for sale on your site. Your PayPal account must have been upgraded from the default "personal" account though to either a "Premier" or "Business" account before you can use this PayPal feature.