On average, listings lease in the $30's per square foot per year. The Jacksonville Beach region is going through a decline in rates. In the last 3 months, the median rate fell $6 per sqft per year. That's a 15% decline in rent.
In the last 90 days, 5 listings have come on the market, which means new availabilities most likley are leasing quickly. 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 1,000 sqft. Most buildings in this market are around 2 stories. Most buildings in this region were built in 1985 and are Class B.