McMaster-carr sells tungsten carbide balls ranging from 1/32" dia. to 1" 
dia.  The 1/8" diameter balls cost $10.32 for a pack of five. 

Swiss Jewel company (Philadelphia, PA http://www.swissjewel.com/).  
sells all sorts of forms in glass, ruby, and alumina.  It has been many 
years since I used them so I can't give current prices.  They do sell to 
industrial customers, and it may work best as a group purchase. 

Dave Sarraf
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