I have a post under collecter cartridges with the heading Kynoch Ammo. I'm not getting much info there, maybe someone here could help if they could check it out, thanks.

See Hambrusch site (under Kynoch) - prices per round:

http://www.ferlachguns.com/

450/400 (3"): 13.60€
450/400 (3 1/4"): 15.70€
404: 10.10 €
375 fl: 9.90-12.40€
300 fl: 9.30-10.50€