I don't see anything on the Finishline website except that plastic one. I have the same issue with it you do. I've fixed it a couple of times.
I have a Flaming River column and hub and the plastic Moto-Lita horn button fits through the Moto-Lita wheel (9-bolt), so I assume the Flaming River horn will fit up for you regardless of what column you have.
I don't care for the aluminum look. I'd prefer black for the horn button. A lot of people have a black horn button with the AC logo on it. Can anyone tell us where to get that one??
http://www.flamingriver.com/index.cf...rod/prd155.htm