9,3x64 is easy to get , 120 -130 euro for 50 RWS cases
just google 9,3x64 Hülsen and it is like this https://www.frankonia.de/p/rws/h%C3%BClsen-9-3x64-50-st%C3%BCck/2006885

beside of Bertram there is now only SHM making 10,75x68 https://huelsenmanufaktur.de/de/produkte

I don't know if this brass is allways on stock. send them a mail about it, think someone there understand english but you can also send it in german.just translate your mail with deeple
https://www.deepl.com/translator
have translate chinese last week and it was completely understandable, its the best just now.