Tom O'Donnell: This must be the lithograph you are looking for: Click here.

The description:

"The Men of '98" Centenary Poster,

lithograph by James Walker, Jones Road, Dublin
76 by 51cm., 30 by 20in.

Framed attractive poster with centrepiece of Father Michael Murphy with vignettes of six other leaders.

If I understand correctly, one copy was offered for sale in an online auction by Whyte's of Dublin on April 23, 2010 but did not obtain the minimum bid of €300 and so was not sold. It isn't clear to me whether you can still bid on this item.