SoundProofing a room? How much would it cost to sound-proof a room of 6m (19'6")...

How much would it cost to sound-proof a room of 6m (19'6") * 5m (16'3"), and what would you have to do?

I give attention to that there is a method of doing it with egg boxes, but it would be difficult getting that plentiful boxes to cover the room.
How much paint?
Answers:    you can put z channel beside 1 1/4 foam then 2 level of sheet rock t think that give you stc 38 then you enjoy to deal next to the door