You have been given excellent advice. I personally own a Trek 1000, and if the price was right as well as the fit, I would purchase a second one, used. Yes, I do love my Trek.

If the size/fit is right, you like how it feels, and the price is right, go for it. The person selling it should be more than willing to let you test it for a few days and take it into your trusted bike store for a once over.

Let us know what you decide.