The typical asking rate per listing is in the $20's per square foot per year. The Casselberry region is experiencing a an increase in rates. In the last 3 months, the median rate increased $5 per sqft per year. That's a 29% rise in rent.
In the last 90 days, 36 listings have been made available, which means leases 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 posted, 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 area are close to 2 stories. Most buildings in this area were built in 1986 and are Class B.