These sell for a little under $800 new. I have seen them for as low as $700 with refurbs/demos going as low as $600. I even know of one guy who claims to have bought a refurb 8x32 LXL for $450 though, I have never personally seen them this low.
I'm not sure but, I also believe that the Nikon warranty is non-transferable. The Nikon refurbs I believe receive a somewhat reduced warranty. (I could be wrong on this account.)
Anyhow, I personally would not be willing to spend more than $400-$450 on this binocular used. I am, admittedly, a bit of a cheapskate so; I suppose you might get somewhere around $500-$550.
If you find someone willing to spend more than that, sell it quick and run as you've just found one of those fools from whom money is quickly parted....