I received a reply from Hunter Pilant of Starline Brass yesterday about the possibility of their producing 375 WIN brass.
In his reply, he stated that “we hope to be producing 375 WIN brass this year."
Might be worth the wait, rather than paying a fool's ransom for the 375 components on Gunbroker that I've seen recently.
Hope springs eternal.
PS: Perhaps more e-mails from interested customers may help build a fire under them to get the ball rolling.
PPS: I have no connection with this company - I just would like to be able to get proper brass for my Win and Marlin rifles in 375 WIN - at a REASONABLE price.