If you're willing to purchase an S, I'd hit that seller up and see if they'll come down a couple of thousand dollars on their price. It's doubtful, because they paid what they paid and they want to make what they want to make off of it, but they have it falsely listed as the wrong trim level, which makes a significant difference in the blue book value.
According to KBB.com, a "fair" purchase price for that exact vehicle (same trim, drivetrain and options, best I can tell from the photos and listing) from a dealer is $20,640 (the range is $18,500 through $22,700, depending on the condition). It looks like a very clean and well cared for Xterra with about 15% higher than average mileage for the age (which isn't uncommon for vehicles in the Inland Empire, since everyone commutes). That being said, the Pro-4X they have it listed as would have a "fair" price of $21,863 from a dealership ($19,700 through $24,000, depending on condition). It seems like they have it priced correctly for an S 4x4, but you could always use the error as a bargaining chip and try. I'd offer them $18,500 since it's an S trim level and see if they play ball. You'll probably end up somewhere between $19,000 and $20,000 if you play your cards right, which is not a bad price. Those small dealerships are always itching to sell cars, so let them know you're very interested but have a tight budget to work with, and that you won't pay a Pro-4X price for an S.
Even better, if you've really got a big pair and want to try your luck, email them a few times asking about their "Pro-4X Xterra for sale" and be sure to be excited that it's a Pro-4X. Drive all the way down there to test drive it and throw a fit when you get there because it's not really a Pro-4X and they "wasted your time." That could score you a nice discount.
