RedShop is free but most if its components and modules are not. So you can download and try out the basic functionality before you decide if you want to make an investment. This recipe will help you install the basic components, the next will take you on a whirlwind tour of the free and paid aspects to help you decide if RedShop is for you.
Make a free account at http://www.redcomponent.com/redcomponent/redshop. Log in to your account and download the free RedShop. Put it on your desktop.
This recipe just uses the free download but the next recipe uses many of the paid for/pro license downloads: