On average, listings lease in the $40's per square foot per year. The Stevenson Ranch submarket is going through a a rise in rates. In the last 3 months, the median rate increased $18 per sqft per year. That's a 70% increase in rent.
Compared to the rest of the Metropolitan Los Angeles market, the Stevenson Ranch region has higher rates, and you'll have to negotiate above asking rent to be in this hot submarket.
In the last 90 days, 4 listings have been listed, which means leases 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 on the market, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 2,190 sqft. Most buildings in this area are close to 4 stories. Most buildings in this area were built in 2003 and are Class A.