The typical asking rate per listing is in the $20's per square foot per year. The Castle Hills submarket is going through a decrease in rates. In the last 3 months, the median rate decreased $1 per sqft per year. That's a 2% decrease in rent.
Compared to the rest of the Greater Austin market, the Castle Hills region has greater rates, and you'll have to negotiate above asking rent to be in this hot submarket.
In the last 90 days, 19 listings have been made available, which means listings most likley are going fast. You'll want to be prepared to make an offer immediately. 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 240 sqft. Most properties in this area are approximately 4 stories. Most buildings in this area were built in 1982 and are Class B.