The link is a generic search on eBay for the term Darkroom Door. The $400 doors currently on eBay are a different auction.
Originally Posted by kb244
I confirmed that they want only $100 for their second door when I picked mine up.
Kevin, that is good advice about not transporting the door on it's side. I had to transport the one I bought on it's side, and I was nervous about it the whole way home. Fortunately, I only live 10 miles away from where I picked it up, and I was able to take old country farm roads _slowly_ the whole way home. Thankfully I did not damage it, but you are quite correct about the fragile construction of this door.