Gentlemen,

a german conmpany named SHM is producing rare cartridge cases in metric and imperial calibers, also in 10,75x68.
I checked today the stock and price, 50 pcs in 10,75x68 are available and offered for 3,30 € each plus shipping.
Of course this is not cheap, but I tested 300 Weatherby and found these cases very good (better than Bertram cases I used in 350/400 Rigby and 11,2x72 Schueler).

Website:
www.huelsenmanufaktur.de

If you need help I can offer support (I am not involved in this company or a relative to the owners)

best regards
Rolf