Most listings are in the $30's per square foot per year. The La Mesa submarket is going through a an increase in rates. In the last 3 months, the median rate increased $8 per sqft per year. That's a 33% rise in rent.
Compared to the rest of the San Diego market, the La Mesa submarket has smaller rates, so you should have no trouble finding a great deal in this discounted submarket.
In the last 90 days, 11 listings have been posted online, which means listings most likley are leasing quickly. You'll want to be prepared to tour spaces as quick as possible. About 36% of the available leases in the La Mesa 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 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 1,370 sqft. Most properties in this market are around 2 stories. Most buildings in this market were built in 1979 and are Class C.