On average, listings lease in the $10's per square foot per year. The Whittier region is going through a decline in rates. In the last 3 months, the median rate fell $10 per sqft per year. That's a 34% decrease in rent.
Compared to the rest of the Metropolitan Los Angeles market, the Whittier submarket has less expensive rates, so you should have no trouble finding a great deal in this undervalued region.
In the last 90 days, 5 listings have come on the market, which means new listings are probably leasing quickly. You'll want to be prepared to make an offer immediately. 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 600 sqft. Most properties in this region are approximately 2 floors. Most buildings in this area were built in 1974 and are Class B.