The typical asking rate per listing is in the $10's per square foot per year. The Seven Oaks submarket is going through a a rise in rates. In the last 3 months, the median rate rose $1 per sqft per year. That's a 3% rise in rent.
In the last 90 days, 35 listings have been made available, which means office spaces most likley are going fast. You'll want to be prepared to make an offer immediately. About 43% of the listings in the Seven Oaks are subleases, so you might be able to sign a shorter term by taking over a previous lease. 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 1,500 sqft. Most buildings in this area are around 2 floors. Most buildings in this area were built in 1982 and are Class B.