The typical asking rate per listing is in the $20's per square foot per year. The Brea region is going through a an increase in rates. In the last 3 months, the median rate increased $2 per sqft per year. That's a 6% increase in rent.
Compared to the rest of the Metropolitan Los Angeles market, the Brea submarket has lower rates, so you should have no trouble finding a great deal in this undervalued region.
In the last 90 days, 4 listings have been posted online, which means new listings might be going fast. You'll want to be prepared to tour spaces as quick as possible. About 25% of the available space in the Brea 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 posted, so finding a space for a small business might be tough.
Even though the median size is 4,760 sqft, there are still 0 leases below 2,000 sqft. Most buildings in this region are around 2 floors. Most buildings in this region were built in 1985 and are Class B.