Larry, my wife is a bell collector and I kinda tag along with her passion.
We have attended several national bell collector conventions and have learned a thing or three about bells.
First, a large bell like you describe will be expensive. No getting around that.
Cast iron will be cheapest, brass more expensive and bronze the most expensive.
The American Bell Association has a web site and forum you can contact:
On the forum you can find the name Neil Goeppinger. He is the best known large bell collector in the ABA, maybe the country. He can direct you to dealers who will be happy to sell you one at heart stopping prices. Sorry, that's the way it is. Write me if you want contact info for Neil.
I would like to have a 30 inch bronze for my house but that is probably not going to happen.
"Folks is funny critters."
Think for yourselves and let others enjoy the privilege to do so, too. ~Voltaire