I have an opposite view of craigslist than most. I invite people to my house. I figure if anything goes down I have home field advantage. I think a potential robber doesn't want to be in a situation like that. First they have to come to an unknown home they never have been in. Second they might not be familiar with the area, which might make them say forget about it and go after an easier or more familiar target. Honestly most craigslist stories I hear about, the robber always meets in a neutral location and the wackos are the ones who want you to come to their house.
And if you are really paranoid you could basically stash a weapon anywhere you like. They just see a newspaper on a counter top, they don't see the knife/gun under it. Also I keep enough cash on me to change any bill so I don't have to leave the room. I just think most robbers would say no to coming to your house. Sure it might scare away real legitimate customers, but no sale is worth me putting my life on the line. Also I have mentioned this before but I don't use email, I always give my cell number. Talking to a person will tell you a whole lot more than an email will.