We live in NW Washington, and in the middle of winter we need to use a heat lamp. Our Marans roosters get frostbite on their poor combs, and then the girls peck at it. We battled with infection on a roosters comb until he passed.
As Egghead pointed out, frostbite is a ventilation problem, not a temperature problem. Chickens can easily handle sub-freezing temperatures as long as the coop is dry and draft-free (plenty of ventilation, but no drafts). Not enough ventilation traps moisture in the coop. That's where the frostbite comes from. By using a heat lamp, you're trying to put a Band-Aid on the symptom without solving the problem.
I'm glad to hear you have a business plan. So many folks here want to hatch the cute chicks but have given no thought what they'll do with the cockerels. What breed or breeds will you be selling?