Sounds like probably a scam. The only way I could imagine this working is that you paypal him the money and he e-mails you information about the tickets. The problem is that you don’t have any guarantee that he’ll follow through and that the tickets are legitimate. I’d do as much research as possible to find out whether printable tickets actually exist or not (maybe call the venue or whoever was the original seller of the tickets) and still, beware, or maybe insist on conducting the transaction in person (in a safe, public place, as always with Craigslist). Good luck! Let us know what happens.