The espresso machine is the bread and butter machine. If you buy one used it needs to be certified reconditioned even if they do offer a warranty. Make sure you ask what all they did to it to recondition it. Did they just clean it up and slap a few parts on it or did they strip it down to the frame and descale all the parts including the boiler in acid. An acid bath means they most likely overhauled the whole unit with new parts and gaskets.
There are some new machines out there that will sell for a few thousand less but not come with any warranty at all. Its all a gamble. 95% of all new machines only have a 1 year warranty anyways. So the likely hood of something failing in the first year is slim at best.
The real key here is to make sure whom ever you purchase a machine from is going to offer repair service for you. If they don't and can't give you a name to someone close I would suggest a different line. A warranty is no good if it takes a repair company 2 days to get there before they can repair your machine.