I have a few bits signed by Jon that I may consider selling for right price.....

Dry County single Digi-pack (UK edition)
These Days CD booklet
Limited Edition cards issued with the Hey God single in UK, reviewing previous albums.

All 100% legitimate. Signed when I was on set with Jon during filming of The Leading Man.

Also have the Lost Highway tour book signed by whole band, but wife will kill me if I sell it.

Oh, and if your friend is called Simon (I know, it's a long shot), I have a black and white photo signed "To Simon, All the Best" and then Jon's signature.
I got it direct from the management team after I contacted them to make a complaint. When I met Jon, he said that if I wanted tickets etc to any of the UK shows (this was back in 96), contact XXXXX and it would be sorted out.
Needless to say, I made contact, never got tickets and I got a bit mad at them. Got the photo from them as apology.