I believe Bud's price is for a used one and not a new one, as for the difference between the other two I can't tell.
I always thought the new hood prices were way over priced, What I have done in the past is to find a really good used one making sure the threads on the hinge connections are fine and the edges of the hood have not been cut, modified or tampered with, every thing else can be repaired, left with stripping it down to bear metal and priming.
This of course depends on the kind of restoration one is willing to do!