So, we recently released a new trial that works on 25 saves instead of 30 days. So if you only need to do a very occasional conversion, it might work better for you.

Subd -> Nurbs conversion has several potential gotchas. That said, I think there's 3 packages that do it that I'm aware of - Maya, T-Splines, and Catia Imagine & Shape. Perhaps SDlib? I've never been able to find an I&S user to talk to about the quality of the conversions. The T-Spline conversions don't handle creasing very well at the moment. Maya has problems with valence 6 and higher. I'd imagine the SDlib conversion is similar to Maya's, I think it's the same author.