I would add that if you do something like buying used, since the pro8200 comes with 3 year warranty, you might want to see if any remaining time on the warranty still exists and if they ever submitted a repair on the unit.
I know some people in the past bought used, and I suggested to them to ask the owner if they used the warranty in the past . You have to find out when and where they bought it, and check the manufacture date on bottom of the unit. If it was never registered and they can make a copy of the receipt you could register it and keep the reminding time on warranty.
Now, some units are manufacture refurbs, and might only have 90 days warranty, so ask about it.
Without warranty, like coderguy says, if you are newbie and the person doesn't live locally so you can check it out, you are taking a chance something could be wrong with it, and to fix these things is expensive.
p.s. I have not registered my pro8200, so if I decide to sell it, I can make a copy of my reciept and let the person know they still have 2 years of warranty on it.