Epp's lists it. They don't say what brand though. Likely Winchester and not cheap. Probably a dollar a shot or more. Old Western Scrounger lists it at $29.95US per 20 for 180 gr cast. Epp's may still be their Cdn. distributor. It's considered to be obsolete, so if Epp's doesn't have any or can't get it, he's going to be reloading.
RCBS makes the dies under their 'Cowboy' dies sets. Wholesale Sports wants $64.99 for the dies, $33.99 per 50 for brass(under Bulk Rifle Brass. Page 6). The case can be formed out out .30-30 cases if need be.
It uses a .320" jacketed bullet. My old Lyman book has some data for a 170 gr jacketed, a 164 gr cast and a 184 gr cast. Let me know if you need it.