If you are serious....
First, lots of money,
Second, secure servers.
And so on.
I would start with the minimum qualifications laid out by iowadawg. The first one disqualifies almost everyone.
"Democracy is two wolves and a lamb voting on what to have for lunch. Liberty is a well-armed lamb contesting the vote." -- Benjamin Franklin
Here you go:
Want to Be Your Own Registrar? MyRebel.com's Registrar Leasing Business Gives You A New Option
Between the cost of the credential and the cost of licensing management software (or having it custom built as most major registrars do) the outlay to start up is likely to run between $50,000-$70,000, plus annual dues of another $8,000 every year.