[ger21]

Since 3D animation is a previous (somewhat current?) hobby of mine, perhaps I can give you some advice. Stay far away from Maya. Especially if you have no 3D experience. Not that it won't do what you need it to do. First, I can't believe your friend paid full price and is going to sell it to you for $500. Second, the learning curve will be incredibly steep. And you'll never use 90-95% of the program.

A little general information about high end animation software. You can model pretty much anything you want in them. From realistic faces to machine parts. They have very few limits, but each works a little differently. (I'm talking generally about Maya, Softimage, 3DS MAX, Lightwave 3D...). For very precise mechanical type parts, go for a CAD system. You can generally model precise parts faster and easier in a CAD package. If you know what you're doing, you can do a lot of things you could never do ina Cad package, but you'll find that Cad packages can do things animation software can't do as well. Most animation packages (the modeling portions, anyway) are much easier to learn with prior 3D experience, as generally 3D is 3D, and is similar in all packages.

AutoCAD. First thing you should now is that Autodesk will not let you transfer AutoCAD licenses. Not sure of the legality of buying it, but you'd never be able to upgrade it. AutoCad is extremely powerful in the 2D department, but you'll find that the 3D is a bit limited. It would be no problem to do your RC parts, but complex 3D parts can be difficult.

If I were you, I'd go the Rhino route for $200. Rhino should do all the 2D stuff you need, as well as more complex 3D stuff than AutoCAD can do.

Remeber, though. You don't always need a 3D model to mill 3D parts.