ebay seller Roberts Camera has a 99.6% positive feedback rating at the time of this post and is labeled as an authorized Nikon reseller.
B&H has the Nikon D610 for $1496.95 (reg. $1996.95) through Dec. 13. Check it out here at B&H Photo.
Additionally, the Nikon D810 is $300 off regular price at $2996.95 through Dec. 13. Check it out here at B&H Photo.
You can find other Nikon DSLR and lenses with holiday savings deals here at B&H Photo.
If you would rather buy a new D610 model, it is on sale as well for $1596.95 and includes a SanDisk 16GB SDHC card, Ruggard Commando 36 camera bag, spare battery and wireless shutter release, along with 2% rewards credit. Check it out here at B&H Photo.