Python, Python Imaging Library and ReportLab Toolkit
Python, Python Imaging Library and ReportLab Toolkit are free instruments. You can download and install them on your web-server at no charge.
You can download Python from: http://www.python.org/download
The documentation for Python is here: http://www.python.org/doc
Python Imaging Library
Should be installed on your server if you want to include images in your pdf files: http://www.pythonware.com/products/pil
You can download ReportLab Toolkit from: http://reportlab.org/downloads.html
The documentation for ReportLab Toolkit is here: http://reportlab.org/os_documentation.html
The instructions regarding installation of the ReportLab Toolkit on a server can be found in User Guide for ReportLab.