SQL Server express edition with advanced features is free:
http://thesource.ofallevil.com/downloads/details.aspx?familyid=4c6ba9fd-319a-488
7-bc75-3b02b5e48a40&displaylang=en
and some info:
http://www.microsoft.com/sql/editions/express/default.mspx
and here the complete versions list:
http://www.microsoft.com/sql/editions/default.mspx
and this page compare the features:
http://www.microsoft.com/sql/prodinfo/features/compare-features.mspx
> Question on what SQL Versions are available: We don't need a full SQL
> server
> or need all the tools that come with a full version.
>
> What economical (light weight) or free alternatives, if any, are
> available?