The typical asking rate per listing is in the $30's per square foot per year. The Lake Forest submarket is experiencing a a boost in rates. In the last 3 months, the median rate increased $31 per sqft per year.
Compared to the rest of the Metropolitan Los Angeles market, the Lake Forest region has less expensive rates, so you should have no trouble finding a great deal in this discounted region.
In the last 90 days, 29 listings have been listed, which means listings most likley are going fast. You'll want to be prepared to make an offer immediately. About 55% of the listings in the Lake Forest 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.
The standard measurement for office space in this area is around 1,260 sqft. Most properties in this area are around 2 stories. Most buildings in this region were built in 1999 and are Class B.