While we may have seen a couple of examples that show a home sold for less than replacement cost, the real answer lies in the general market not just onesies and twosies. What got me started on this is the listing in Grove for a relatively modest home, x distance from the beach listed for $800k. What counts are sold prices but I don't have access to sold homes/lots data. I do not have the ambition to tackle Walton County's database.
As a general question, how much would a lot cost that is an "easy" walk to the beach, say less than five minutes? Add to the cost of the lot, say $300k for a 2,000 SF home and you have the central question: can I buy an existing home for less than ($300,000 + cost of the five-minute-walk-to-the-beach lot)?
My mother has a brand new home in Cypress Breeze Plantation. It's 2,200 sq. ft., 4 Beds, 3 Baths, 12' ceilings, granite everywhere, stainless professional series appliances. In addition, it comes with a 2 story carriage house that is 968 square feet.
Cypress Breeze Plantation is a 5 minute walk to the gulf. Cypress Breeze has the largest pool in Walton County. To children, the pool is like Disney World.
Her home is listed in the low 400's. I thought it couldn't be beat, but there is potential to buy the right vacant lot and build the same home for 10% less. It depends on your construction costs and time frame.