Any help would be greatly appreiciated.
Is it a facsimile of her signature or the real thing? If it's not the real thing, this isn't worth any more than you paid for it, and probably less than that.
I got the book 80% off on amazon too! I don't think it's her real signature, I have it on my copy too and it would be worth much more if it was. People sell autographs on the internet for hundreds of dollars, and imagine what her autograph would go for, JK Rowling is one of the top 10 most famous celebrities.
If it is really signed by J.K rowling than it must be worth something. However, I know that it may not be that special to have a deluxe edition anymore, because Amazon.com is having an 80% off sale that brings the value of the deluxe edition to $13.00. Hope this helps: )
I dont think it'll be worth much anytime soon, but sometime in the future it'll be worth something (depending on it's condition), after all it is a collectors item.
If the sig is real, it is rarer. You could sell it on eBay and earn a few dollars.