You might try figuring out what makes/models used that particular part, then searching for someone parting out a machine with it (such as say, used tractor part shops, they are out there, just don't seem to advertise a lot).

Alternately, if your existing part isn't too bad, it may be able to be fixed up by a machine shop or they could possibly make a new one using it as a model.

Take the part to a machine shop and see what they'd charge to make it. Sometimes it isn't too bad.