Most listings are in the $50's per square foot per year. The Solana Beach region is going through a an increase in rates. In the last 3 months, the median rate went up $59 per sqft per year.
Compared to the rest of the San Diego market, the Solana Beach region has more expensive rates, and you'll have to negotiate above asking rent to be in this hot region.
In the last 90 days, 6 listings have been posted online, which means office spaces most likley are leasing quickly. You'll want to be prepared to make an offer immediately. About 150% of the listings in the Solana Beach are subleases, so you might be able to snag a great spot on a short term. There aren't many listings below 2,000 square feet posted, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 2,000 sqft. Most properties in this area are approximately 2 floors. Most buildings in this area were built in 1988 and are Class A.