It's really great that she got the time to write that because I bet there are many out there who have already fallen victim to such theft. Of course you'd be excited to find memoriabilia signed by JK, but personally, if I got something signed by Her Geniosity, would I really go and sell it on e-bay?
Take everything with a pinch of salt! You can never tell how far Voldemort's clutches have gone around the world. You know, due to all the false rumours and such false stuff, it's a wonder we all don't have high blood pressure.