On average, listings lease in the $10's per square foot per year. The Orange region is going through a decrease in rates. In the last 3 months, the median rate fell $1 per sqft per year. That's a 7% decline in rent.
In the last 90 days, 2 listings have come on the market, which means new availabilities might be going fast. You'll want to be prepared to make an offer immediately. 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 1,200 sqft. Most buildings in this market are close to 2 floors. Most buildings in this area were built in 1984 and are Class B.