I'm brand new to this forum but I must say it is a wealth of knowledge and in this case I have a little to depart. I used to sell on ebay (notice "used" to cause who needs the headaches) anyway I had a very similar experience a about a year ago when I was selling. I sold a Gucci canvas shopper that I had personally bought at saks so I knew it was the real deal. I used it a few times then it kinda got forgotten in the closet so I sold it on there for a really modest price (around $400 well under half what I paid) anyway the lady left positive feedback, said it was perfect etc etc. Never heard from her again until August of this year ( I sold the bag right after christmas of 06) she says it is a fake bag, she demands her money back. I responded and said I was sorry but the bag was real and offered to provide her with a copy of my credit card statement. She says no she just wants her money back and she is going to call the police on me! I told her that if she wished to get in touch with my local authorities to please do so and I would provide them all the necessary proof of purchase. I didnt hear from her again until about 2 weeks later I get a package in the mail. It was a fake gucci bag, and I mean FAKE it has plastic trim and the inside lining was white with guccii written in hot pink script. She then emailed and said she had proof she sent me the bag, I just responded and said thanks that I now had proof that she was a scammer. i told her that I had asked the postmaster to open the box since I was not expecting it and that he had and he filed a report about the counterfeit item with proof of the sender (that was a lie on my part) but it worked. I never heard another word from this con artist.
You handled this one very well. See it can happen!