On average, listings lease in the $30's per square foot per year. The St. Augustine submarket is seeing a a rise in rates. In the last 3 months, the median rate went up $32 per sqft per year.
In the last 90 days, 2 listings have been listed, which means new availabilities are probably leasing quickly. You'll want to be prepared to make an offer immediately. About 300% of the available space in the St. Augustine 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 on the market, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 2,000 sqft. Most properties in this area are around 1 floors. Most buildings in this market were built in 1986 and are Class B.