The typical asking rate per listing is in the $30's per square foot per year. The Miami-Dade County submarket is going through a a rise in rates. In the last 3 months, the median rate rose $9 per sqft per year. That's a 28% rise in rent.
In the last 90 days, 387 listings have been listed, so you'll want to check back regularly for new listings. About 4% of the available leases in the Miami-Dade County are subleases, so you will probably have to consider a longer term 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 1,950 sqft. Most buildings in this market are close to 3 stories. Most buildings in this region were built in 1982 and are Class A.