On average, listings lease in the $30's per square foot per year. The Riverhead submarket is going through a decline in rates. In the last 3 months, the median rate decreased $2 per sqft per year. That's a 6% decrease in rent.
In the last 90 days, 2 listings have been listed, which means new listings are probably going fast. You'll want to be prepared to make an offer immediately. There aren't many listings below 2,000 square feet available, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 1,500 sqft. Most buildings in this region are close to 1 floors. Most buildings in this area were built in 1990 and are Class B.