I would call $700 for a 7/10 a /fair/ price. Not a bad price but not a great price either.
$750 for a pristine AF-D model is a good price if you are patient in the markets I play, but I do mean patient. This isn't what I would consider a "high volume" lens on Craigslist.
So what is your time worth to you? are you willing to wait three, six months for a better condition one comes by at the same price or for a $600 7/10? If I were buying for use, not resale, I wouldn't be.
So Long As It's Perfectly Functional, and I do mean Perfectly, I'd pay $700 just to get it in my hands today.
I assume the hard case is present and in good order? I also assume the tripod collar is in good order, and so is the M/A switch? These are the three items I most often see damaged.