Steel Rain...
I am not sure that I understand your question completely, but in most cases a file is generated for CNC cutting by a CAD/CAM program. There are also many pure CAD (computer aided design) programs that work fine for the design aspect and a good number of CAM (computer aided machining) programs available in a multitude of price ranges.
The most popular with small CNC users are CAD/CAM, where both the design (drawing) and the toolpath generation are done within the same program. Most of these are also able to import .dxf or .dwg format files from most any CAD program. Most producers of high end CAD/CAM titles also have a lower end, entry level offering. These start around $150. Two examples would be Vectric's "Cut2D" and Delcam's "ArtCAM Express". Both are entry level with similar features. Both offer an upgrade path that will get you some credit of the purchase price applied to one of that providers higher priced titles. Both allow "try before you buy". Few, if any, will allow you to cut your product with a demo version.
Here are links to the mfgr's webpage:
Vectric Cut2D:
http://www.vectric.com/products/cut2d.htmlDelcam ArtCam Express:
http://www.artcam.com/express/