If the price is less than $6, I think you will pay for extra fee , for example , the DNS fee or the some other valued added service. I don't like the registrar less than $6, since I know that the cost of the registrar will be $6.0-$6.3
you can try CNOBIN, it is powered by Bizcn.com,Inc. an ICANN Accredited registrar. their price is $6.59 ; eNom is ok, while the price is $6.69 and the prepayment to become their best reseller account will be greatly different from CNOBIN(just require $500). And I apply for a one just require $300 in their promotional period
Maybe you can have a query from its support team.
Good luck!