"a) build it so that you can license the technology to people that have made a company "

Better yet a white label website that refers business back to the reseller or registrar and can be operated as a subdomain to the resellers or registrars main website ie suggest.registrarname.com. Do this on a monthly fee basis that is reasonable not per name registered.

"b) become a reseller or registrar so that you can fully deliver the service and collect the recurring revenue."

Reseller makes sense. Becoming a registrar doesn't. Using this as the cornerstone of an idea will never result in enough to cover the ongoing costs.