It depends on the kind of coding certification you have or plan to get. Whether it's from a local community college in Durham, one from an online school, or a national qualification.
Two of the best medical coding certifications in Durham are the CPC from AAPC or CCS-P from AHIMA. While AHIMA is an older organization, AAPC is the largest for coding/billing and also quite popular among health care employers in North Carolina. Both are national organizations and their qualifications similarly accredited. http://www.squidoo.com/medical-coding-certification-exam-study-guide
In North Carolina, focus on the CPC medical coding exam. CPC stands for Certified Professional Coder while AAPC stands for American Academy of Professional Coders.
If you have this certification then you can expect your annual salary to be anywhere between $35,000 and $42,000 for coding jobs in NC. However, the average pay in Durham is between $53,000 and $65,000 which comes to an hourly pay of $29/hr. This is much higher than the national average for medical billers and coders: http://medicalcodingcertificationexam.blogspot.com/2011/12/medical-coding-and-billing-salary.html
I have seen this trend around Durham, in places like Chapel Hill, Carrboro, Cary, Apex, Raleigh, Wake Forest, Holly Springs, Garner, Graham, Fuquay-Varina, Burlington, Clayton, Henderson, Sanford and Smithfield.
Remember that CPC is an exam-based credential. You need to pass the CPC exam to get certified.