Godaddy also has a reseller program that you can get into for $99 a year. That would give you an automated platform to operate on.
Here's the description from the site:
~Very competitive buy rates!
~Sensational assortment of money making products for you to sell, including domain names, email, hosting, Web site builders, Internet utilities and more!
~The ONLY reseller program with Private Domain Registrations!
~You set your prices - and make the margins you want and need!
~Instant Domain Reseller sites put you in business fast!
~Best-in-industry systems and 24/7 support!
~No deposit, No advance purchases and No minimum sales required!
Just visit goddaddy.com and click "Reseller Program" in the top nav. menu.
also offers an automated reseller plan that includes a lot of features. You may think about that option before setting up your own system. If I could I would opt for the automation.