If anyone was born to sell real estate, it is Mark Costanza. This Corning/Horseheads native can trace his interest back to elementary school, getting reprimanded for selling candy to fellow students. He has always had the entrepreneur embedded deep down. Spending the summers in south Florida with his grandparents, helping them work on "flip" homes, got him hooked on homes and real estate in general, at such a young age.   With the technology boom...