Got my refurbished Nikon 500 f4 AF-S VR coming from Calumet tomorrow, it's stated it's refurbed by Nikon.
I am assured that it is Mint and complete so I'll let you know what I find - I looked at a number of used lenses from the usual dealers and found that the refurb, (assuming the description of what 'refurbished' means is correct), appeared to be a far better deal for the money.
Time will tell but for me it's a new(er) lens for not much more than, in some cases, a very old one ... Camera World also have them and I guess a few other of the main dealers.