On average, listings lease in the $20's per square foot per year. The Rancho Santa Margarita region is going through a decline in rates. In the last 3 months, the median rate fell $11 per sqft per year. That's a 34% decline in rent.
Compared to the rest of the Metropolitan Los Angeles market, the Rancho Santa Margarita submarket has less expensive rates, so you should have no trouble finding a great deal in this discounted region.
In the last 90 days, 15 listings have been listed, 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 850 sqft. Most buildings in this market are approximately 2 floors. Most buildings in this region were built in 2002 and are Class A.