Most listings are in the $10's per square foot per year. The Montclair region is experiencing a decrease in rates. In the last 3 months, the median rate fell $26 per sqft per year. That's a 57% decrease in rent.
Compared to the rest of the Metropolitan Los Angeles market, the Montclair submarket has less expensive rates, so you should have no trouble finding a great deal in this undervalued region.
In the last 90 days, 0 listings have been made available, which means leases might be going fast. You'll want to be prepared to make an offer immediately. About NaN% of the available leases in the Montclair are subleases, so you will probably need to consider the implications of signing a direct lease with the building. 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 1,030 sqft. Most buildings in this region were built in 1979 and are Class B.