Upload & Sell: Off
Not that I can afford either camera but I think the D700 won't drop that much.
The D800, if rumors are to believed, seems to be a mini-D3X rather than a D700 replacement so the D700 owners will not be upgraded. There will be some that will but not in droves.
When there is a D700 replacement, at least I believe there will be one, then I could see the D700 dropping hopefully under $1700. If it gets to $1500, I will jump on that.
Also never use eBay as an indicator. At least look at closed auctions, anyone can set a price, doesn't mean anyone is going to buy it for that plus you have to realize the seller is trying to cover his PP + ebay + shipping fees.