Bone Domes
Hi rafmatt,
The number of civvies flying Jet Provs and Hunters is a tiny proportion of a small total flying community of private pilots. You won't get fat supplying those alone.
Your custom helmet business would probably have to include at least the sky-divers, para-motors, two-axis microlighters and para-gliders to make money, and perhaps even the motorbike guys as well. I suggest you visit all their clubs and have a look.
I don't know what helmets the Jet Prov and Hunter guys are using. My guess would be it would be a mixture, probably mostly Alphas and Gentexs. Maybe one of them will reply to your enquiry. Or you could visit somewhere like North Weald and have a look.
Good luck with the new business; I hope you can make it work.
BP.