Most listings are in the $20's per square foot per year. The Rancho Santa Margarita region is experiencing a a rise in rates. In the last 3 months, the median rate went up $1 per sqft per year. That's a 3% increase in rent.
Compared to the rest of the Metropolitan Los Angeles market, the Rancho Santa Margarita region has lower rates, so you should have no trouble finding a great deal in this depreciated region.
In the last 90 days, 20 listings have come on the market, which means spaces most likley are going fast. You'll want to be prepared to tour spaces as quick as possible. There aren't many listings below 2,000 square feet on the market, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 1,000 sqft. Most buildings in this region are around 2 floors. Most buildings in this area were built in 2002 and are Class A.