u/Ready-Car-2340

Hello advanced D&Ders! I was going through my dead dads stuff and found a 1987 TSR #1031 Forgotten Realms Campaign Set, still in the original shrink wrap, with an Ed Greenwood signature on the actual box underneath a small opening in the wrap.
I also have the original 1987 receipt, which has “signed by Ed Greenwood” written on it, and I know someone who witnessed it being signed at a gaming con. Does anyone know roughly what this would be worth?
Let me know if you have any questions about it I’d be happy to answer!
Thanks!