Easy DIY Fix on the AC vent!
Call Phil at PartsShop and see what they run, I think $200 is a little high. The metal tabs push in or pull out, I can't remember which one and then the left side of the unit will slide out. You need to detach the "adjusting screw" control wheel as well with a 4mm allen wrench. Just shine a flashlight in there and take a look in the upper right area of the control wheel.
With tools and parts in hand, you should be done in 5 minutes including beer time.
Let us know if you have any further questions.
Also, check out the "search" button in the upper right area of this page and type in Chicago in the search field and select "good MB Shops" in the select forum area, you should have at least 5 hits.