Most listings are in the $20's per square foot per year. The DFW Metroplex region is experiencing a an increase in rates. In the last 3 months, the median rate rose $1 per sqft per year. That's a 3% increase in rent.
In the last 90 days, 2930 listings have been listed, so you'll want to check back regularly for new listings. About 3% of the available space in the DFW Metroplex are subleases, so you will probably need to sign a longer term lease with the landlord directly. There aren't many listings below 2,000 square feet available, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 2,032 sqft. Most buildings in this market are approximately 2 stories. Most buildings in this area were built in 1985 and are Class B.