I emailed RCBS too, and they gave me a number to call in MN (Dealer services). I'm not a dealer, but called the number and left a detailed message mentioning that it would be for a group buy and I also asked about quantity and pricing. Hopefully they will call me back.
Lee emailed back and said the custom services for sizing dies has been reopened. The response leaves me wondering if they even read the details of my original inquiry or my reply email, so I asked the questions again. Hopefully I can get a good response from them. I figure because it is Friday, I probably won't get a response until Monday.
I'll see what information I can find out about C4HD, and hopefully between one of the three companies there will be something favorable.