You should check with the builder to see if they want to build on a lot outside of their community. I talked with one of the track home builders last week and they were reluctant to build out of their subdivision beacuse of scheduliing and unsure about demand for lots they already owned.
Check with a couple of the custom builders, like Potter hill, Freedon Homes, Schumacher Homes, TK Builders, Anderson Homes, etc., to name just a few. These companies are set up to build on your lot.
But do contact a Realtor. That way you willl have someone to guide you through the process, and help you find the special incentive "deals" when available. Note; Builders do not charge you more when you use a Realtor to assist you. They build our cost into their marketing expense.
If you have any further questions, you can contact me.