The typical asking rate per listing is in the $30's per square foot per year. The Jacksonville Beach submarket is going through a an increase in rates. In the last 3 months, the median rate went up $32 per sqft per year.
In the last 90 days, 5 listings have come on the market, which means listings most likley are going fast. You'll want to be prepared to tour spaces as quick as possible. About 20% of the listings in the Jacksonville Beach are subleases, so you might be able to sign a shorter term by taking over a previous lease. 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 710 sqft. Most properties in this market are approximately 2 floors. Most buildings in this region were built in 1985 and are Class B.