500 4th Avenue, the love child of Robert Scarano and Isaac Katan, has finally hit the market. So far, 79 out of 135 units have popped up on StreetEasy. Listings range from $342,000 for a 539-s.f. one-bedroom to $1,426,000 for a 2,789-s.f. two-bedroom. The average price per square foot of $706 is less than the Argyle and The Crest but slightly higher than Novo. GMAP