Bruce, click on this link:
www.nardiusa.com/hornbuttons.htm
Then click on "horn buttons" located on the right side of the page then click on "ultima group" at the bottom of the page This will open another window, Horn button 1 of 8 is very similar.
Nardi USA, sold via Perfect Motion sells this horn button assembly, (as I remember) for about $155.00
I'm sure if your price were less, many members would be happy to purchase your button