Several years ago I was lucky enough to purchase a 1985 Live Aid Poster signed by Madonna, Bono, Elton John and (even though he wasn't at the original one) Robbie Williams. Someone reckoned that autographs are tripling in value and, although I don't want to sell it, I would be interested if anyone would hazard a guess as to the value of this now. I won't say how much I paid just to see if paid right for it. It is definitely genuine and has a certificate of authenticity. Thanks
Pity nobody could give you an answer for this. You could phone your local auctioneers and ask them. They're usually very helpful and don't, in my experience, put pressure on you to sell.