I found one called Skybound VisualStyles
. The website has the following information about it:
Skybound VisualStyles gives your applications the true look and feel of Windows XP and later Windows operating systems. It overcomes the serious limitations of the visual style support included with the .NET framework.
VisualStyles provides both a drop-in Windows Forms component that can extend your existing application with zero code, and a set of classes that can be used to custom draw your own controls using the Windows Theme API. It was designed using .NET framework conventions and integrates easily into any application or component library.
Their license basically says that it can be used for free, but you resell it under your own name. I tihnk that if you do want to do that you need to buy a license for $99.95, but otherwise it's free
EDIT: Found this information. It clarifies the license:
This program is completely free for commercial or non-commercial use. Full C# source code is also available for just $99.95.