i suggest you get an an arduino, some servos of various sizes, and a 6v power supply, and start experimenting. Also look at hvac dampers that are available to find inexpensive ones that might fit your needs, or get ideas for making your own.
That's what I'm thinking as well. Not sure if I want to get the uno or maybe a mega. The reason is that the servo library for the uno is limited to 12 servos. I'm gonna need 14-15 servos if I ever get this project going. I've also heard it might be easier and cheaper to just buy 2 unos and link them somehow. Anyways these are the dampers that are currently in my ducts.
I have the 6" single bearing model.