3. The Reverend Natural Light
"There's probably many more suppliers, but that's a place to start.
It's usual and customary to weasel some cash from the seller if you
still have an inspection contingency. My place had the same problem.
The seller just wanted the problem to go away so he offered $850 back
at closing, which I accepted. $250 will go towards the parts for the
fan/ducts and the other $600 will buy a lot of beer. "

While I do as much work myself as possible, this is one that I most
likely would get a pro to do. When it comes time to sell the house,
I'd rather be able to point to a system that was professionally
installed and be able to tell them the company that did it. I think
many potential buyers may be concerned about whether it was done
correctly or not, get cold feet and walk, meaning it may be harder to
get the top offer when you try to sell.