He’s just hedging to see how badly you want it. Don’t look too desperate. He doesn’t have a good chance of selling such a specific domain, so maybe offer $50 or something. If he says it’s worth a lot more than that, just say you’ll get a .net address or something and wish him well selling it. He might weaken then. (That approach has worked for me.) Remember that he’s just being greedy, whatever happens. This is an industry of pure greed and nothing else.