I am looking for links or samples in diagramming options in Windows 8 XAML / C #. I will also consider any third-party options.
I need to provide a graphical solution including bar graphs, pie charts and line graphs
You can take on the charts available in the free WinRT XAML Toolkit .
Try telerik
http://www.telerik.com/products/windows-8/controls.aspx
If this looks expensive, you can create something yourself based on the blog article below:
http://blogs.msdn.com/b/metroapps/archive/2012/07/24/building-pie-chart-for-windows-8-metro.aspx
Arun
I participated in porting Visiblox to WinRT. We are currently in beta and will be released in the next few weeks.
http://www.visiblox.com/visibloxcharts-for-winrt