Sebastian,
there a bunch that are still cheap if you need any better than a home brewed... well cheap, depends on your budget...
smoregrava,
I only used 2D CAD for this simple stuff, no need to go into 3D unless I had needed a 3D rendering... same for the CAM part; basic 2D.
I should have a personnal WWW corner soon with the details of this probe along with some ideas to share with all CNC enthusiasts. I'll bookmark this thread so I'll announce when it'll be out off my HD and free on the WWW. Still, the CAD I'll have there will be 2D DXF. Maybe I could share the CAM files too...