I'm pretty sure he is talking about the half weight balls. Used to be we could find a 14 /12, 15 1/2 # balls. Didn't have to drop a full pound in weight. Now a days they are called blems.
Still, to answer the question, don't know of any specific web site, just check them all, maybe give their customer service a call and see what they have.
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Charter Member FOS
Have Balls - Will Travel