The best I can offer is to buy from a reputable online camera retailer, preferably one that has a live chat facilty or a telephone number so you can ask a question about it and if they can guarantee the serial number is not on the 'bad' list. Ask them to confirm by email that it's not a bad one so you have proof. Pay by credit card so that any hassles and you can make a claim to get your money back. Personally if I had to buy online I'd make sure that the company also had stores throught the country so that if it came down to it you could drive to one of them even if it's a great distance, then at least you can make your demands face to face with someone who is real and can't avoid you.
EDIT> I would just like to add that my camera has just been returned this very minute.
That's 3 days short of 2 months for a 2 week fix. While I'm delighted to have it back, I'm extremely disappointed with Nikon for not replying to me in those 2 months. I sent mail by special delivery at a cost of £4.95 a time. Though I have my camera back I still intend pursuing my complaint