Most listings are in the $30's per square foot per year. The Rancho Santa Margarita submarket is going through a a boost in rates. In the last 3 months, the median rate rose $1 per sqft per year. That's a 2% increase in rent.
Compared to the rest of the Metropolitan Los Angeles market, the Rancho Santa Margarita submarket has lower rates, so you should have no trouble finding a great deal in this undervalued submarket.
In the last 90 days, 10 listings have come on the market, which means new listings most likley are leasing quickly. You'll want to be prepared to tour spaces as quick as possible. 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 1,240 sqft. Most buildings in this market are around 2 floors. Most buildings in this region were built in 2002 and are Class A.