A full function homemade blower door you can build for $30
I was really impressed that Gary built a blower door from a discarded furnace blower.
I think that about a year ago, I had a photo of one of those blowers on EcoRenovator with an idea that a DIY Blower Door could be done, but he actually did the deed!
He has a wonderful write-up (as usual) and lots of references. Very thorough, very doable.
Best,
-AC