On average, listings lease in the $30's per square foot per year. The San Marino region is going through a a boost in rates. In the last 3 months, the median rate rose $36 per sqft per year.
Compared to the rest of the Metropolitan Los Angeles market, the San Marino submarket has smaller rates, so you should have no trouble finding a great deal in this undervalued region.
In the last 90 days, 1 listings have been posted online, which means office spaces might be going fast. You'll want to be prepared to make an offer immediately. About 200% of the listings in the San Marino 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 620 sqft. Most properties in this market are close to 2 floors. Most buildings in this area were built in 1951 and are Class B.