I personally use VectorWorks on an occationally basis. I actually started using it when it was a 2D cad program called BluePrint that later evolved into Minicad which had some 3D capabilities.
At that time my choices were Blueprint, PowerDraw, and TurboCAD. These were the the low cost options, about $200 or so. I've seen TurboCAD for Windows but I think Mac support was dropped long ago. PowerDraw, I think is marketed has PowerCAD.
If you want something inexpensive, I think you will be out of luck. The downside to Vectoworks is that you have to purchase third party plot drivers unless you have your own plotter.
Maybe try a Google search or Download.com
I do have some old disk for BluePrint and Minicad I may be interesed in selling. Drop me a private message if you are interested. I might even still have my TurboCAD disks.