I am a crafter/hobbyist ("maker") - where can I find a good 3D CAD software which is inexpensive or even free?
For your maker activities, you can download and use e.g. the free 3D CAD modeler and fabrication tools based on Autodesk Inventor Fusion - Autodesk 123D Design and 123D Make.
"123D" is a family of free 3D solid modeling and fabrication software tools based on the same Autodesk technology used by millions of designers and engineers worldwide. Autodesk 123D is easy to use - you can design precise and makeable objects using smart tools that let you start with simple shapes and then edit them into more complex shapes. The Windows, Mac and cloud/mobile applications "123D" support many standard file formats.
You can also combine "123D Design" with "123D Catch" (Photofly/Photo Scene Editor) to make a 3D model of a real-world object from a series of photos.
For 2D CAD work you can use another Autodesk simple and free tool - the cloud version of AutoCAD - AutoCAD 360 (WS).