I just got the X850XT from the refurb newegg section of the site. It is not guaranteed that you'll receive the manuals and whatnot, but it is possible. I've gotten 2 things from them (including an NF2 mobo) refurbed, both the mobo and the video card came with the open retail box and all of the stuff.
Now you have to ask yourself if it's worth the chance, but since you already have a PSU and hopefuly some SATA cables laying around then you should be set.
My guess is these people sent back the mobo's after finding out that they weren't SLI moddable.
BTW, DFI has a 1 year warranty, if you receive this and it doesn't work I BELIEVE you should be able to send it back. (If the manufacturers still honer it since it's a refurb purchase)