Most listings are in the $30's per square foot per year. The Claremont submarket is going through a a boost in rates. In the last 3 months, the median rate went up $6 per sqft per year. That's a 24% rise in rent.
Compared to the rest of the Metropolitan Los Angeles market, the Claremont region has higher rates, and you'll need to pay a premium to be in this hot region.
In the last 90 days, 4 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. There aren't many listings below 2,000 square feet posted, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 610 sqft. Most buildings in this area are approximately 1 floors. Most buildings in this area were built in 2008 and are Class B.