Most listings are in the $20's per square foot per year. The Hawthorne submarket is going through a a rise in rates. In the last 3 months, the median rate went up $26 per sqft per year.
In the last 90 days, 1 listings have been posted online, which means office spaces most likley are leasing quickly. You'll want to be prepared to make an offer immediately. About 100% of the listings in the Hawthorne 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 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 1,800 sqft. Most buildings in this area are close to 2 floors. Most buildings in this market were built in 1987 and are Class B.