I know this is an old thread, but for those that are interested, Zippo lighters have dating codes on the bottom to tell when they were made. This one appears to be authentic to me. Worth the asking price? Not from me is isn't. I have paid less for cars.
I actually used to collect vintage lighters ( I know, pretty lame) but some do have a pretty decent value amoung collectors, with Zippo being amoung the most collectible. Especially if it is one of the first models with the hinge on the outside of the case.
http://www.zippoclick.com/collecting/dateCodes.aspx
Anyway, thought I would chime in on something I know a little about. Not affilated in any way with this seller.