If you are looking for free software or trail software of SQL Server reporting services, you have couple of options.
1. Free edition – SQL Server Express Advanced edition
The free edition has some limitations, but the best part of it is, it is free. It provides all features that a beginner will typically need.
You may download the free edition here - http://www.microsoft.com/express/sql/download/
Remember to choose 'SQL Server Express Advanced Services', which include the reporting services.
2. 180 day Trial edition of SQL Server Enterprise edition
This is the fully functional version of the most advanced edition, that comes with all features of SQL Server. However, the trial will expire after 180 days.
You may download the trail edition of SQL Server Enterprise edition from here - http://technet.microsoft.com/en-us/bb851664.aspx
If you like to pay and buy SQL Server license, you may purchase it as part of MSDN subscription or buy it from one of the Microsoft partners. Depending on the license and edition you choose, it may cost several thousand dollars to purchase SQL Server. Reporting services is part of any paid edition of SQL Server.