Is this a good deal? D700.....

You don't buy a camera if you can't afford it. Resale value is not something you should really be considering at purchase time, there are hundreds of factors, both within and outside your personal control that could affect resale value.

Look, there are hundreds of places where you can rent a D700.

Go rent one for a week. If you don't get on with it after a week, you're not going to get on with it "long term".