On average, listings lease in the $30's per square foot per year. The San Marino region is going through a a rise 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 higher rates, and you'll need to pay a premium to be in this hot region.
In the last 90 days, 1 listings have been made available, which means new availabilities most likley are leasing quickly. You'll want to be prepared to make an offer immediately. About 100% of the available space in the San Marino are subleases, so you might be able to find a shorter term or below market rent. 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 around 2 floors. Most buildings in this area were built in 1951 and are Class B.