Most listings are in the $10's per square foot per year. The Louisville region is going through a decrease in rates. In the last 3 months, the median rate fell $3 per sqft per year. That's a 14% decline in rent.
In the last 90 days, 19 listings have been listed, which means listings most likley are leasing quickly. You'll want to be prepared to make an offer immediately. About 5% of the available leases in the Louisville are subleases, so you will probably need to consider the implications of signing a direct lease with the building. 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 1,610 sqft. Most buildings in this market are around 2 stories. Most buildings in this area were built in 1999 and are Class A.