I guess $389... I got my AG-3 for $250, but I'm special... and it has a much more distinct "D" than the for sale, at least for an AG-3.
Yes on your D. I went back to look at the OP and couldn't see the reverse very well. I am going to believe that NGC saw the D.
Select the forum you want to post in, "coin chat", "U S Coins", etc., and there should be a "post thread" at the top of the page.
To me, the most important part of getting a 1916-D was the Mint Mark... Nice, Clear, and Blatantly Obvious. I can see the one on the coin for sale, but only half is really there... but obviously a D.