Most listings are in the $20's per square foot per year. The Irving submarket is seeing a decrease in rates. In the last 3 months, the median rate fell $1 per sqft per year. That's a 3% decrease in rent.
Compared to the rest of the DFW Metroplex market, the Irving region has greater rates, and you'll need to make a great offer to be in this hot region.
In the last 90 days, 352 listings have been made available, so you'll want to check back regularly for new listings. About 4% of the office spaces in the Irving 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 posted, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 650 sqft. Most properties in this area are around 2 stories. Most buildings in this area were built in 1985 and are Class B.