1 The average office space in the United States is around $39 per square foot according to CushWake.com. 2  An office building in Indianapolis will run around $25 per square foot. 3  An office building in downtown New York City will run around $65 per square foot. An office building in Indianapolis will run around $25 per square foot. 2  An office building in downtown New York City will run around $65 per square foot. 3  Office space in Washington D.C runs anywhere from $45 to $52 per square foot.