A quick google search turned this up:
http://www.nydmv.state.ny.us/titlestat/default.html
Looks like you can search for free in NY state. Wish we had that in Ontario - it'd save hundreds per year at work.
Personally, I'd never buy a car without checking the lien status unless it was from a close personal friend or relative. Even then I'd still probably check it. Imagine watching a tow truck come take your new-to-you Porsche away, and you being left with no recourse.
Chris