Visual3D.Net Beta is a XNA engine and it looks great. But you can find a few more XNA engines out there. Two examples:

Blade3d :

http://www.blade3d.com/Home/tabid/36/Default.aspx
Look at their galery: http://www.blade3d.com/MediaGallery/tabid/74/Default.aspx#viewLocation


Sorcerer's engine :



Water shader moving:
http://www.youtube.com/watch?v=Q3aQ-pRkDUM
Features implemented:
* Scene editor
* Switching between fullscreen or windowed mode
* Switching resolution
* Fps displaying
* Pause system
* Importing heithmaps for terrains
* Camera moving around
* Loading .FBX and .X models
* Shaders ( Yes, shaders )
- Multitexturing
- Mirror
- Water
* And it works with XBOX

Now, why am I posting this? As a info. You can also making your own engine with XNA and it is free and easy to use. You can even sell it as those guys.
Also, don't ask me for price about my engine, because I am not going to sell it. I am making it just for a learning purpose.
So, go ahead and start making your own engine. You will see how easy you can do it.