The Ventubes Replacement Front Air Vent are available at this Vantage Plane & Plastics ventube page and also from Aircraft Spruce ventube page for under $100 for a pair. And they work for most models of Cessna single engine aircraft: Cessna 120, 140, 150, 152, 170, 172, 175, 180, 182, 185, 190, 195, 205, 206, 207, 210 thru F, and 305's.
One thing I wondered was what they would look like in my plane. I did not see any pictures of it. So here are a couple pictures.
Here is one with it closed and locked. It looks pretty similar to the original except it has the bumps around the side to help twist the outside.
Here is a picture with it out and extended. It once again looks pretty similar to the stock one.
I read the instructions which looked pretty easy, and my A&P put them in. He said it was easy. I had him transfer the temperature probe over from the old vent as well which was simple for him. There is a 337 Form to file for the STC, but that is not too hard for an A&P.
So the plastic ventubes do not look fancy, but they work great and look pretty similar to the original vents. If you have the original stock vents, I highly recommend you get a pair.
/Brian