SQL Server 2012 Express is the free and lite version of the Microsoft database offering for small stuff. Some of the opportunities SQL Server Express edition provides is extensive, for example, someone running a Microsoft Access database can take advantage of linked tables on SQL Server instead of storing the data inside Access. This might be enough to keep the I.T. Department happy for now, brings a new world of development and management capabilities to the database and sets your database up on a much more scalable platform as things take off.
In SQL Server 2012 there are 3 editions to download, Express, Express with Tools and Express with Advanced Services (which includes Tools), the latter which provides a level of Reporting and Data Integration capability. You might as well download the Express Edition with Advanced Services as you get a level of capability to use Reporting Services and SQL Server Data Tools, whether you need it now or not.
Asides from the extensive list of limitations http://msdn.microsoft.com/en-us/library/cc645993(v=SQL.110).aspx its a pretty cool offering from Microsoft.
The main risk in running Express edition databases is potential for loss of data – there is nothing out of the box that creates scheduled backups – you need to do this yourself. The following reference outlines how to achieve unattended backups – create a stored procedure for the sole purpose of executing a backup of your databases which can then be scheduled using Windows Task Scheduler http://support.microsoft.com/kb/2019698 and sqlcmd.
You can run along and download your copy of SQL Server 2012 Express here http://www.microsoft.com/en-au/download/details.aspx?id=29062.