I have no idea if Road Warriors was the proper place to ask this question, but I'd still tell you to pass on this particular bike and keep on looking.
There are lots of 250's running around for sale, a lot of them with few miles and no real problems. Widen your search a bit and find one of those. No need to settle for an abused Ninjette (unless the guy only wants a few hundred $$ and you're mechanically competent enough to see it back to roadworthy status).
Also, welcome to the forum. It's a hoot.
2012 Honda NC700X
; '90 PW50