Domain Name Resellers?

I own KryptonicWave.com which provides reliable hosting, and developer resources for customers. I want to provide to my clients domain name registration as a new feature. What i'm looking to do is create a whois search and domain name registrations through my site. Since I like to customize everything on the site I would like to fully customize the form and images within the form and within the results that are produced. Anyone know a company that resells domains without the purchasing of credits needeD? Or if anyone knows what i'm talking about please let me know.