there are a few free modeling programs out there
Blender:
I've tried it and it was hard to get into, but it's free so I'm not complaining. 
http://www.blender.org/
GMax:
The much better choice. Think of it as a dumbed-down version of 3ds Max. AutoDesk has since stopped offering GMax since it has both 3ds Max and Maya under it's belt, but you can still find some websites that still have it for download.
http://www.turbosquid.com/gmax