Gil;
I got samples from a company and have passed the information to the two major gunsmithing suppliers. One is interested. This may be good news. The company I contacted was Stockcap.
I believe that you have to buy a minimum number of each size from the manufacturer. If I remember correctly the number is 1000 pcs.
I have been thinking about what size I want to standardize my plugs at. I used the samples with good success this last week. I had four leather covered pad jobs to do ....so I did. I tried several sizes from large to small. I didn't like using the small plugs...too much give and Barge cement is unforgiving when tacky. I will be contacting them about an order though.