I would get a new one if I could. It's possible that a local store still has one that hasn't been sold. That way, you know the history and can contact Sony if it goes belly-up for no reason.
Still, if you end up getting anything pre-owned, go to the store. It doesn't look available online, but I know that GameStop used to upsell warranties on used systems to extend from 30 days to a full year. Not sure what that would run you, but it would give you some peace of mind.
Lastly, I have no idea what is up with the "refurbished" terminology now. Prior to the 360/PS3/Wii era, it would mean that the system had stopped working and was fixed. With hard drives in the mix, stores would have to send anything that could store music, movies, etc. off to get wiped at a warehouse (was really dumb), and would get returned as "refurbished." Now Sony, Microsoft, and Nintendo are all selling refurbished systems directly as well. I guess these are more likely to be the "system broke and was fixed" variety, but you still can't look up a console's history the way you can with a car.
So again, get a new one if possible.
cur iustus satus scribens latine