On average, listings lease in the $10's per square foot per year. The Dallas County region is going through a an increase in rates. In the last 3 months, the median rate went up $16 per sqft per year.
In the last 90 days, 32 listings have been posted online, which means new listings most likley are leasing quickly. You'll want to be prepared to tour spaces as quick as possible. About 25% of the office spaces in the Dallas County are subleases, so you might be able to find a shorter term or below market rent. There aren't many listings below 2,000 square feet available, so finding a space for a small business might be tough.
Even though the median size is 2,770 sqft, there are still 0 leases below 2,000 sqft. Most properties in this region are close to 1 floors. Most buildings in this area were built in 2003 and are Class A.