On average, listings lease in the $20's per square foot per year. The Green Park submarket is going through a a rise in rates. In the last 3 months, the median rate rose $22 per sqft per year.
In the last 90 days, 17 listings have been listed, which means new listings most likley are going fast. You'll want to be prepared to make an offer immediately. There aren't many listings below 2,000 square feet posted, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 1,550 sqft. Most buildings in this region are close to 2 stories. Most buildings in this market were built in 1985 and are Class B.