Most listings are in the $20's per square foot per year. The Fullerton submarket is experiencing a decrease in rates. In the last 3 months, the median rate fell $2 per sqft per year. That's a 6% decline in rent.
Compared to the rest of the Metropolitan Los Angeles market, the Fullerton region has less expensive rates, so you should have no trouble finding a great deal in this depreciated region.
In the last 90 days, 14 listings have been posted online, which means leases are probably leasing quickly. You'll want to be prepared to make an offer immediately. About 129% of the listings in the Fullerton 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 available, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 1,160 sqft. Most properties in this market are close to 2 stories. Most buildings in this area were built in 1973 and are Class B.