joggmc1,
just a question: do you need balls for small (let's say up to 2" 1/2) or larger valves?
In the first case, here in Italy there are many Suppliers in the Brescia district, for example...
for a U.S. source. There are fewer suppliers out there after so muuch of the industry moving off-shore. You might have to consider Asian sources if your quantities would justify the hassles of importing the parts. Check Google for "valve ball", and you will even get your eng tip post!