Hi Chris,
Nice to see you've joined the forum. I bought some plate cutters from Jaroslav recently; yes he does take a bit of a time to reply to your emails, but he'll eventually reply. He will now do the heads with a 1/2" outside dia socket for a bit extra, as he knows more people shooting warbows need them. Mine cost around six euros each and I have now case hardened them, so they are sharp and hard enough to scratch glass - I'll be using them at the Triskell when you come over.
Cheers, Dave