Most listings are in the $20's per square foot per year. The Brea submarket is experiencing a a rise in rates. In the last 3 months, the median rate rose $2 per sqft per year. That's a 6% rise in rent.
Compared to the rest of the Metropolitan Los Angeles market, the Brea region has lower rates, so you should have no trouble finding a great deal in this depreciated region.
In the last 90 days, 4 listings have been listed, which means leases might be going fast. You'll want to be prepared to make an offer immediately. About 25% of the office spaces in the Brea 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.
Even though the median size is 4,760 sqft, there are still 0 new availabilities below 2,000 sqft. Most properties in this region are approximately 2 floors. Most buildings in this market were built in 1985 and are Class B.