I own an N6 and an N4/N6 one-off hybrid. I have owned an N4.
Great guitars. Really well built, love the naked wood, great punchy tone and playability. Really dig the Stephen's Extended Cutaway (SEC)
I still have the first two I mentioned, but sold my N4 as the neck was too thin for my taste after time. There's a lot of variability in the neck thickness on N4 from what I understand. The hybrid one I have (N4 neck, N6 body)has a nice chunky one on it. It's made of beautiful (heavy) Paduak wood and sounds AMAZING.
At $250, you're probably looking at the import N2 which doesn't have the extended cutaway (it has standard bolt-on)and also has cheaper woods/electronics.
N4's come with Bill Lawrence L500 in the bridge and a Seymour Duncan in the neck, and the N2's have stock Washburns I believe.
It's highly unlikely that you're being offered an N4 there. N4's usually go for at least $800 . I got a steal on mine here on RT for $600-ish!
If your seller doesn't know, ask for a photo of the neck heel. Look up pics of the SEC and you'll see the obvious difference.
There's also a newer N24 import model out there, but I've never seen or played one.