On average, listings lease in the $50's per square foot per year. The Lake San Marcos region is going through a a rise in rates. In the last 3 months, the median rate went up $53 per sqft per year.
Compared to the rest of the San Diego market, the Lake San Marcos region has higher rates, and you'll have to negotiate above asking rent to be in this hot region.
In the last 90 days, 5 listings have been listed, which means new availabilities might be 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 690 sqft.