Yes, you should work with a buyer's agent. The buyer's agent is representing your best interest not the builders.
The agent on site is working for the best interest of the builder.
Durham North Carolina  area Builders commonly require that your buyer's agent be present, and sign in, the first time a prospective purchaser visits a site before payment of commission even is discussed. At times when buyers use an advertisement to find the development themselves first, builders can refuse to pay any commission regardless of how helpful an agent may become later in the process. It is advisable to call the development first and inquire about their policy on compensating real estate agents if you are using one.

I'm Willie Velez a Broker, Realtor and ABR® (Accredited Buyer's Representative) serving Durham North Carolina and the Triangle Area. - I specialize in working for home buyers, representing their best interests throughout a purchase. And just so you know, using me as a buyer agent won't cost you anything.  My services are paid for by the home seller.

When I work for you I will:

1) Educate you about Buyer Agency, outlining my fiduciary responsibilities to you, which include: complete Disclosure, Loyalty, Confidentiality, Obedience and Accountability.

2) Save you time searching the market for an affordable home that meets your criteria.

3) View homes with you and provide comparative analysis. I can also refer you to expert home inspectors who'll provide more in-depth analysis and advice.

4) Help you explore your financing options so you make the best possible mortgage decision.

5) Negotiate the best possible price for you and take care of all the documentation details.

6) Assist you, if necessary, in finding any home-related services you need.

In short, I'll provide you with comprehensive, high-quality buyer's service.