1904 signed photograph St Pius Xth

I have a  signed Photograph of Pope Pius Xth taken on May 30th 1904 as witnessed by Fr J.A.O'Leary OSB during an audience with the Pope on that day. It has been in my uncle's possesion for many years. How much do you think it is worth and where would I be able to find out the best place to let it go to?

The photograph has been expertly framed in relatively recent years (last twenty). On the reverse is the handwritten authentication by the Priest who witnessed it, of the Pope's autograph.