This Is the first problem with my car that I'm really concerned about
 

Just a few days ago I notice a vibration sound while I was In My Car. The sound is like when a person has their car sound system too loud and it sends a vibration through the rest of the frame. It happens in that first and second second when I shift from park to go either forward or backwards then it goes away once i'm driving. Its just that second before the car begins to roll it happens then goes away. ANy help is appreciated. Thanks guys. (2005 Automatic)

trans mount perhaps

Just incase that is the problem, Is it an expensive repair?

yes. i had a avid one on my car so it was slightly more aggressive than the stock one but i had the same problem with my car. i just kept it because it made the car more readable on the track.

i'm just addressing this to make sure its a problem and not just you thinking its a problem. Are you shifting at any appropriate time or launching and shifting at a rather low rpm? It could be the exhaust drone in low rpm, if mine gets too low (around or under 1k) and is put under acceleration it sounds like a small sub is in my car.

It's an auto shift. and yes it only happens at very low rpm around 1k just when the car is about to roll then it goes away. It never used to happen so im worried that its a problem that will get worst.