It's always good to be cautious but for what it's worth I have bought 6 guitars on Ebay, Parker Fly, Strat 12 string, Strat 1997 special edition, PRS McCarty, PRS Artist 1V and a Godin LGX-SA. I've never been let down. Just make sure that the seller has loads of positive feedback and is preferably living in the same country as you.
Good luck in your hunt for a Chet Atkins but I think you might have to wrench it from someones cold dead hand