This how-to tells you how to properly remove the side and main vent pieces, you can finally get that lost change outta there!
Insert a butterknife on the underside of the vent. push-n-pry until you hear a "pop", that's one clip undone. Now, grab onto the vent, and put the knife on the side of the vent closest to the center of the dash. now push-n-pry until you hear another "pop", that's 2 clips. now just pull up and out (towards the door).
The Main Vents
Insert a butterknife underneath of the bottom side of the vent and pull up. Then pull on the vent. You will hear a 'snap', but that's just the clips popping out of place. Once you have that out, you'll have to remove the actual vent from the circle. Just pull on the black vent portion and it will pop out. Now, the little vent aimer thingy, it's inserted between 2 plastic pieces that makes it able to spin in a direction. pop the directioner thing out. You will see what I mean when you do it. Then you will haev to remove the circle from the vent tube. there are 4 clips (2 at the top and 2 at the bottom). Unclip, and pull on the circle.