All exotic Coleoptera (including Sun Beetles) with the notable exception of Goliathusgoliatus are VERY difficult to acquire from breeders in the US if you are not associated with a scientific institution. Simply, this is because they are illegal without the proper permits. AND even if you hold the proper permits most people breeding them for institutions are not likely going to trade with hobbyists. Therefore I honestly think your best course of action would be to apply for import permits from the USDA and FWS, though there is no guarantee you would get them.
Alternatively you could also volunteer or work with an institution that possesses them, a strategy which has allowed me to work with species such as Dynastes hercules, Megasoma elephas, and many more.
Roach Crossing has two species listed on their site, but from what I've heard, people aren't able to get in touch with them and they may be defunct? If anyone has done recent business with them, I'd love to hear about it because they have a number of species I'm interested in.
Yeah I believe it is very difficult to get in touch with them, though they are still posting stuff. Also a little bit suspicious of anyone selling Pachnoda sp given the strict regulations surrounding them.