Hello Curt

I've been trying to find something affordable to convert a poly mesh to nurbs and finally came across http://www.resurf3d.com/

They have a RhinoResurf plugin (for Rhino of course) to do this, and 2 stand-alone applications:

Mesh2SingleNurbs - I have tested and purchase this and have produced some reasonably good nurbs approximations. I can tell you is that the surfaces are not perfect, but they might be usable for you. I have not tried editing them in other applications.

PointCloud2Nurbs - I have tested this and was unable to get any of my files to produce anything usable. The demo file supplied with the app did work, but it had too few points to be useful for me. Might work for you though. I was using pointclouds with 0.5 - 1.0 million points.

You can download fully functional demos (time limited) to see if they will work for your purpose.

Good Luck,
Chris