Hi there,
SugarCRM has an Open Source edition that is free, along with Professional and an Enterprise editions that cost money. You can find out about the differences between the editions by visiting
this page on the SugarCRM website.
There's a podcast that describes what Commercial Open Source business model. Go to
this link and scroll down to the third podcast from the bottom.
Finally, though the Open Source edition is free from fees, you'll need to budget time and/or money in maintaining and administering the system, making customizations to tailor the system to fit your business needs, backing up data, and all those other tasks that you would do with
any business system.