btw.. I have sold "Sealed In Box" items on craigslist before. Here's what I typically offer them:
1) Give me the money first, but I'll let you open the box right there in front of me to make sure it turns on and fits the item description (meaning, i didn't sell an iPad 2 to you but calling it iPad 3, or something like that)
2) If it doesn't work, I'll give you the $ back. If it works and you decide not to buy it anyway, sorry.. you are SOL.
Anyways, maybe you can ask for that when you are buying it. If the situation is sketchy, I will typically use my phone to record a verbal agreement to the above before the transaction.