I am no authority on how well used products survived, but I bought an ES-1 off a fellow AC'er back in the fall. I had it drop shipped to another AC'er, so that he could play around with it, and he then shipped it off to me.
It survived all those shipments, and performed fine for all 3 of us. I subsequently sold it to a good friend, who is using it presently, so I think that if it is a good one, it should be a good one for a while.
Good luck with the hunt,