123d beta 9 is not 123d designer, alternatives?

In my exploration in 3D modelling last year 2012, I've researched for a good CAD program below 1000$. It seemed that there are a lot of options like SketchUp, Autodesk, Alibre, FreeCad, and a lot more. Since I'm an EE, I mostly build simple and small cases or structures for electronics. Usually simple structures below 5x5x5cm's.

Please note that I'm using the applications for hobby usage only. 

So my time is limited to just several hours a week. I'm sure with certain applications you can make the best objects if you master the application thoroughly, however, I'm more looking for a quick fix where the application can be productive the very first few hours.

I've started with SketchUp (Free), moved on to Alibre (paid, below 1000$), then Autodesk 123d (free) beta 9 and now Cubify Invent (50$).