If you are interested there is a CAM extension to Inkscape which works nicely but does have a learning curve much like that of CNC-Toolkit. Personally I am looking to migrate to Aspire or their Vcarve/3D carve package as the system i am currently using costs me about 3hrs edit time for any serious g-code set up (that gets very expensive fast when this makes products I sell). I understand the cost issue very very well and will say that saving the money and getting a good system is worth it. If you want to start with CNC-Toolkit or Inkscape with the CAM extension that might tide you over till you can afford a better system.

Best of Luck.