It isn’t really what the bike is worth itself. It’s the market that set’s the price. The ninja 250 is a very popular bike with a lot of people. $1,000 is fair.
For example, I bought a 2008 Ninja 250 last year for $3,600. At the end of the summer I sold it to a guy in Cali for $4,100. This was mostly due to the fact most dealerships were on backorder for 3-6 months with this bike. So the only way to get one quick was to hope someone was selling one outright. The bike was only worth $3600 when I bought it, but I sold it for $500 more. Same principle basically.