Why do you believe there is a need for a Buffet operation? Is there competition? What is the population you will be drawing from? What is the mix of menu items? Are you themed? Oriental, North American, or other? Will you be serving breakfast, lunch dinner?
Buffet can be profitable if the volume exists. Low volume (customer counts) low quality! Freshness and cooking in small batches to maintain quality and food safety.
Labour cost is not necessarily diminished by having a buffet, was that your reason for selecting that concept