Autodesk has 123D, a budget modeler targeted at hobbyists, especially those designing for 3D printing. Some have a 3D printer at home, others have access to a local fab lab or a hackerspace, or they make use of service providers such as Shapeways. At the fab labs that I visited, Rhino is the standard tool for 3D design. Here people have access to the software via University licenses. However, hobbyists would need to pay the full price, which is steep.
What about a budget “maker edition” of Rhino?
The difference to the professional version: When saving a model, it is uploaded to the Internet under a Creative Commons license.