Milkshape and Blender are about as cheap and low quality as you can get. Geo3D, Solidworks and Alibre are a few good ones. I'm positive all three of them cost money, but they don't cost too much.. I know Geo3D and Solidworks do because I have both, but I'm not sure about Alibre. If money isn't an issue then I recommend Autodesk Inventor. I've had it for years and use it for making models for so many things such as racing games, Blockland, general use, etc.
Also you're going to need a program to export the models if you want them to work for BL. I believe Milkshape will do that.
