Even more than a great buy, be sure that is not a great fraud.
Make your due diligence on why it has a so catchy price. Maybe ask him to use escrow? Check the recent nameservers/whois data change?
I'd say it is a good buy as general recommendation.
That would be a superb deal for $150 but as mentioned by @alinask - proceed with caution, make sure you check it out properly and make sure it's not a scam.