Generating Facebook accounts in bulk is not easy. I'm not suggesting that it's a panacea, but if you're looking for something to indicate a real purchase this

Generating Facebook accounts in bulk is not easy. I'm not suggesting that it's a panacea, but if you're looking for something to indicate a real purchase this would be strong. If someone logs in with Facebook and has 10+ friends then I'm going to say they are 99% legit. Plus you can look at their profile manually if you're in doubt. Of course you also offer email but those orders get more scrutiny. HN is an echo-chamber of hate for Facebook login but the real world (and I suspect your target market) does not share this.