Silverlight Navigation Menu

I am using the Silverlight Business Application Template. The navigation consists of a few HyperlinkButtons in a StackPanel. I would like to create a more robust navigation menu (multilevel) with dropdowns and such. Telerik has one for silverlight (http://demos.telerik.com/silverlight/#Menu/FirstLook)

I don't want to use Telerik control because its too expensive and I have tons of开发者_如何学JAVA problems with Telerik. I've Googled it but including "Navigation" in my search seems to only include results about the navigation framework.

Anyway, anyone have a good example?