I ordered this one for only 10€:
http://www.pearl.de/a-PX8527-5480.shtml
and it is quite perfect.
It can be easily connected to my car and can be changed / drawn in every direction you want and then can be fixed.

I have the keyboard open (closed works as well) and an aux cable connected to the line out jack.

On the left side the power connector is not 100% free, so I have to cut a little bit from the holder.

But the experience is great.

Even phone calls come over my in car radio and I can talk free.

I also tried to do this by bluetooth and it works with clear sound, too.
This solution in combination with no power connection gives you a cable free solution until the battery runs out.

Music, navigation, phone calls - the perfect car entertainment system!