Domain Name Registrar

Expensive hobby.

Registrar Accreditation: Financial Considerations
US$2,500 non-refundable application fee, to be submitted with application.
US$4,000 yearly accreditation fee due upon approval and each year thereafter.
Variable fee (quarterly) billed once you begin registering domain names or the first full quarter following your accreditation approval, whichever occurs first. This fee represents a portion of ICANN's operating costs and, because it is divided among all registrars, the amount varies from quarter to quarter. Recently this fee has ranged from US$1,200 to S$2,000 per quarter.
Transaction-based gTLD fee (quarterly). This fee is a flat fee (currently $0.20) charged for each new registration, renewal or transfer. This fee can be billed by the registrar separately on its invoice to the registrant, but is paid by the registrar to ICANN. 

Also requires proof on financial backing:
liquid capital immediately available in the applicant's name at the commencement of the accreditation period in an amount of US$70,000 or more before the ICANN accreditation becomes effective.