Personally, I would recommend Rhino 4.0. It is an extremely easy to learn platform and combines 2D and 3D design quite well. Plus there are really good render engine plugins like Vray.
Rhino is also very good at importing and exporting a wide variety of different file types from Autocad to Digital Projects to Maya. I don’t know the exact pricing but it is cheaper than Autocad and has a very good users community.