I'd say run away. I had a chacne a few weeks back to buy a excelent looking Marlin camp 9 for $200 bucks from a craigslist ad. Guy's emails said "dave" at the bottom, we conversed via email, he sent me several pictures from different agles, depicting an in-tact serial number, so i'm thinking this over pretty seriously.
Next morning i call the number he sent me in the emails and i ask for dave. "dave? you must have the wrong number man" so i hang up and email the guy...."you must have typed your number in the email wrong, tried to call you but guy who answered said tehre was no 'davd'"
email he responded with said "ooh, that's just a name i use to sell stuff" and "and sorry, i already sold the gun, it was my buddy's form out of state he just wanted me to get rid of it for him"
I'm saying think seriously about running away from this. IF you do go check it out, take someone with you, preferably an LEO you have a close relationship with. MY bro-in-law's with the Sherifs' dept he was going to come with me on the buy if "dave" hadn't ended up so sketchy