Be sure to contact your local Builders and Contractors Association (if your area has one) and contact the Better Business Bureau prior to your purchase. See if there are any complaints filed against the builder. Ask the builder for a list of homes that they have sold in prior years, and take a drive by them to see how they look today.
It is advantageous to get a buyers agent that is able to assist you in your purchase. If you choose not to hire a buyer's agent, then you may want to have an attorney review the builders contract, terms and financing options before you sign anything.