The typical asking rate per listing is in the $10's per square foot per year. The Imperial Beach region is experiencing a a boost in rates. In the last 3 months, the median rate rose $18 per sqft per year. That's a Inf% rise in rent.
Compared to the rest of the San Diego market, the Imperial Beach submarket has smaller rates, so you should have no trouble finding a great deal in this depreciated region.
In the last 90 days, 2 listings have been listed, which means new listings are probably 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 780 sqft. Most buildings in this region were built in 1990 and are Class A.