I'm selling my 2013 Model S (Performance 85 KWh) with 27,000 miles on it. The car has pretty much every extra available at the time. Black outside, beige inside, piano black interior trim, 22" gray wheels. Delivered to me on March 31, 2013, and has been trouble-free for four years. Recently had a full annual checkup by Tesla and has two new rear tires (fronts are about 50%).
KBB estimates the value of this car at roughly $55,000 to $56,500. The car is located in Miami, FL. PM me if interested in greater detail.
EDIT: I should also note that my car lives in an air-conditioned garage, and that I don't drive much (obviously, given only 27K miles in 4 years), so I only charge to 75% normally and then full-charge to 100% about 4-5 times a year to balance the pack. The result is that my battery still shows 260 miles of rated charge when I do a full charge: 98% of original capacity. This gives you an idea of what condition you should expect to see on this car.