What do with eBay Camera Fraud?

Hi, I recently was trying to sell my Nikon D200 through eBay, and it sold, so I presumed, that someone legitimate bought it, and then I got a message from a man claiming that he wanted me to send this item to Nigeria, I've gotten this scam before so I know that it's a scam, and haven't done anything.
But can anyone give me a step by step explanation of what I need to do, it appears as if he has 'technically' put the money in my Paypal account, but from what I've read they get there money back by taking it out as soon as I send the item (claiming I misinformed them in some way), or claim that the item was damaged and get it back from Paypal.
Any suggestions on how I should approach this and what I should do so I'm not liable for anything? Sorry, this is stressing me out a lot! Thank's so much for your time.

Added (1). Actually I was wrong in my first assumption, there's no verification that he has put money into my paypal account, so I simply deleted the listing and reported him. Is there any way that I could still be liable though?

Tell him you want a physical check mailed. Then cash it. If it bounces, (obviously) don't mail him the camera, but if it goes through, go ahead and mail the camera. You have to make it crystal-clear to him that you're not going to send the camera until you have the money.

If you reported him you are not liable for anything. There's no money - that paypal email they sent you was probably fake. If you go to paypal.com and there's no money in your account then no money was sent