On average, listings lease in the $20's per square foot per year. The Centereach region is going through a decrease in rates. In the last 3 months, the median rate decreased $8 per sqft per year. That's a 26% decrease in rent.
In the last 90 days, 3 listings have been listed, which means spaces 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 750 sqft. Most buildings in this market are around 1 floors. Most buildings in this region were built in 2001 and are Class B.