You know, I was wondering exactly the same thing today. I'm having a similar issue, someone who saw a wheelset I have for sale on craigslist, and asked if I would ship. He plans to pay with Paypal using a credit card and asked if that would be ok with me. WHich of course I have no idea!
Paypal seems safe, once the payment is made - but I too would like to hear what the TE collective wisdom says...